Crystalline to Crystalline Phase Transformations in Six Two

Subscriber access provided by Kaohsiung Medical University

Article

Crystalline to Crystalline Phase Transformations in Six Two Dimensional Dynamic Metal-Organic Frameworks: Syntheses, Characterizations and Sorption Studies Fazle Haque, Arijit Halder, and Debajyoti Ghoshal Cryst. Growth Des., Just Accepted Manuscript • DOI: 10.1021/acs.cgd.8b00664 • Publication Date (Web): 20 Jul 2018 Downloaded from http://pubs.acs.org on July 22, 2018

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 30 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Crystal Growth & Design

Crystalline to Crystalline Phase Transformations in Six Two Dimensional Dynamic Metal-Organic Frameworks: Syntheses, Characterizations and Sorption Studies Fazle Haque, Arijit Halder and Debajyoti Ghoshal* Department of Chemistry, Jadavpur University, Jadavpur, Kolkata, 700 032, India E-mail: [email protected] ______________________________________________________________________________ ABSTRACT Six dynamic metal-organic frameworks namely {[Cd(1,4-bib)(glut)].(4H2O)}n (1), {[Zn(1,4bib)(glut)].(4H2O)}n pydc)].(2H2O)}n

(4),

(2),

{[Co(1,4-bib)(3,5-pydc)].(2H2O)}n

{[Zn(1,4-bib)(3-mglut)].(4H2O)}n

(5)

(3),

{[Mn(1,4-bib)(3,5-

and

{[Zn(1,4-bib)(2,2′-

dmglut)].(2H2O)}n (6) from 1-(4-(1H-imidazole-1-yl)butyl)-1H-imidazole (1,4-bib) using four different dicarboxylic acids salt [disodium glutarate (Na2glut), pyridine-3, 5-dicarboxylate (3,5pydc), 3-methyl glutarate (3-mglut), 2,2′-dimethyl glutarate (Na22,2′-dmglut)] and four different divalent transition metal ions have been synthesized. Out of these the structure of compound 3 has been previously reported although synthesized in different method, whereas rest of the compounds are new. All of these synthesized compounds are characterized by single crystal and powder X-ray diffraction and other physicochemical methods. All the compounds exhibit 2D structure as evident by single crystal X-ray studies. Interestingly, all of these compounds show crystalline to crystalline phase transformation. Variable temperature PXRD study indicates compounds 1 and 6 show single step phase transformation and rests show two steps phase transformation upon desolvation. All of these transformations have also been established by IR spectroscopy. Among the said structural transformations 1−5 show reversible crystalline to crystalline phase transformation on desolvation and resolvation whereas 6 shows an irreversible transformation. All of these transformations are thoroughly investigated by PXRD and IR spectroscopy. Sorption studies with CO2 and N2 were also performed for all the metal organic frameworks and characteristic surface adsorptions are found in all the cases. ____________________________________________________________________________ INTRODUCTION In the past few decade, the metal-organic frameworks (MOFs) have garnered a great deal of attention because of their intriguing structural features as well as their fascinating applications in

ACS Paragon Plus Environment

Crystal Growth & Design 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 2 of 30

the field like catalysis,1-4 gas adsorption,5-8 magnetism,9-12 luminescence13-16 etc. In the mission of including multiple properties in MOF the search of multi-functionality on a single MOF has been explored vividly.17, 18 Recently researchers have concentrated their attention in the flexible coordination polymers for such multi functionality where flexible framework can undergo structural transformation by the application of external stimuli like heat,19 light,20 pressure,21 magnetic field,22 electric field22 etc by individually or in a cooperative manner. Thus there is a possibility that each of the phases can exhibit different applications to the mentioned field and as a result the entity can be used as a multifunctional material.17,

18

Sometimes, structural

transformability of a flexible MOF occurs through a change of host guest interaction which makes such of materials suitable for the application in many other field like selective gas adsorption/separation,6, 8, 23 chemo-sensing,14 asymmetric catalyst,1, 3 drug delivery24, 25 etc. Some recent study also indicates some advance applications of flexible MOF in ferromagnetic,26 nonlinear optical (NLO),27 OLED materials;28 data storing as well as stimuli responsive switches 29-31

etc. It is evident that the flexible MOFs suits for better functionality in some cases due to

two major reasons. One is the ease of introduction of a variety of functional groups in the void surface i.e. in the organic linker, which may behave differently in response to the external stimuli; and secondly the guest molecules or the exchange of guest molecules that sometimes, may play a crucial role in directing the structures of metal-organic frameworks.32, 33 The flexible MOF can be prepared by using metal nodes and flexible organic ligands or by preparing MOFs containing weak non-covalent interaction (π−π stacking or other supramolecular interactions and hydrogen bonding).34, 35 One of the most common features for the flexible MOF is the structural transformations occur due to release or exchange of solvent molecules36 and this happens via internal bond rearrangement, change in coordination of metal ions, change in conformation of flexible ligands in MOF37, 38 etc. The transformation may occur by mainly two ways, crystalline to crystalline transformation and crystalline to amorphous transformation.39 Recently, our group has reported about both of such transformations40, 41 where it has been noticed that the crystalline to crystalline transformation is mostly observed phenomenon for flexible MOFs. Interestingly, the ease of transformation can be monitored as, one definite structure is transforming to another definite structure.40, 41 and it is needless to mention that such studies are potentially useful for the tuning of transformation in flexible MOFs to obtain a definite pathway for getting required structural arrangement for a particular application.


Page 3 of 30 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Here to study such transformation process in an lucrative manner, we have synthesized five new and one previously reported (3)42, 43 mixed ligand metal-organic frameworks namely, {[Cd(1,4bib)(glut)].(4H2O)}n (1), {[Zn(1,4-bib)(glut)].(4H2O)}n (2), {[Co(1,4-bib)(3,5-pydc)].(2H2O)}n (3), {[Mn(1,4-bib)(3,5-pydc)].(2H2O)}n (4), {[Zn(1,4-bib)(3-mglut)].(4H2O)}n (5) and {[Zn(1,4bib)(2,2′-dmglut)].(2H2O)}n (6) from 1-(4-(1H-imidazole-1-yl)butyl)-1H-imidazole (1,4-bib) using four different acids salt, disodium glutarate (Na2glut), pyridine-3,5-dicarboxylate (3,5pydc), 3-methyl glutarate (3-mglut) and 2,2′-dimethyl glutarate (Na22,2′-dmglut) and four different metal ions. All compounds have been characterized by single-crystal X-ray diffraction, powder X-ray diffraction and other physicochemical methods. All the compounds except 1 and 6, exhibit two steps crystalline to crystalline structural transformations whereas compound 1 and 6 show a single step crystalline to crystalline transformations. All of these structural transformations are confirmed and thoroughly investigated by VTPXRD experiment and IR spectroscopy. Structural analyses of the transformed phases have been executed by indexing the PXRD data of the respective transformed phases. With all of the activated compounds, gas sorption analysis has also been performed. The details synthetic scheme of compounds 1−6 has been shown in Scheme 1.

Scheme 1. Synthetic outline of complexes 1-6



EXPERIMENTAL SECTION Materials 1-(4-(1H-imidazole-1-yl)butyl)-1H-imidazole were synthesized by earlier reported literature procedure.44 The starting materials imidazole and 1,4-dibromo butane for the above synthesis were purchased from Sigma-Aldrich Chemical Co. Inc. and used as received. High purity cobalt(II) nitrate hexahydrate, zinc(II) nitrate hexahydrate, cadmium(II) nitrate tetrahydrate, manganese(II) nitrate hexahydrate, glutaric acid (H2-glut), 3-methyl glutaric acid (H2-3mglut), 2,2′-dimethyl glutaric acid (H2-2,2′-dmglut) and pyridine-3,5-dicarboxylic acid (H23,5-pydc) were also purchased from Sigma-Aldrich Chemical Co. Inc. and used without farther purification. Na2glut, Na23-mglut, Na22,2′-dmglut and Na23,5-pydc were synthesized by the slow addition of solid NaHCO3 to respective acid suspension in water in a 1:2 ratio. After neutralizing the acid (checked by pH=7), the solution were allowed to evaporate to dryness. All other chemicals including solvents were of AR grade and used as received. Physical measurements Elemental analyses (carbon, hydrogen and nitrogen) have been performed using a Heraeus CHNS analyzer. Infrared spectra (4000–400 cm−1) has taken on KBr pellets, using a PerkinElmer Spectrum BX-II IR spectrometer. Thermal analysis (TGA) has been carried out on a METTLER TOLEDO TGA 850 thermal analyzer under nitrogen atmosphere (flow rate: 50 cm3 min−1), at a temperature range of 30–600 °C with a heating rate of 2 °C min−1. X-Ray powder diffraction (PXRD) patterns of the bulk sample were recorded on a Bruker D8 Discover instrument using Cu-Kα radiation. Sorption Measurements The N2 (77 K) and CO2 (195 K) adsorption isotherms were measured for the dehydrated frameworks of 1−6 using Quantachrome Autosorb-iQ adsorption instrument. High purity N2 gas (99.999% purity) and CO2 gas (99.95%) were used for the adsorption measurements. The low pressure volumetric adsorptions for N2 (at 77 K, maintained by a liquidnitrogen bath) and CO2 (at 195 K, maintained by dry ice-acetone cold bath) were performed in the pressure range 0−1 bar using the dehydrated samples in all cases. At first the as-synthesized compounds of 1−6 (∼40 mg for each) were taken in the sample tube and dehydrated at 423 K, for 4 h under a 1×10−1 Pa vacuum prior to measurements of the isotherms. Then the helium gas (99.999% purity) was introduced to the gas chamber and let to diffuse into the sample tube by controlling the valve. The gas adsorption volume was calculated from the difference of pressure (Pcal−Pe), where Pcal is the calculated pressure without any gas adsorption and Pe denotes the observed pressure at equilibrium.


Page 4 of 30

Page 5 of 30 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


SYNTHESES {[Cd(1,4-bib)(glut)].(4H2O)}n (1). An aqueous solution (20 mL) of disodium glutarate (Na2glut) (1 mmol, 0.162 g) was mixed with a methanolic solution (20 mL) 1-(4-(1H-imidazole-1yl)butyl)-1H-imidazole (1,4-bib) (1 mmol, 0.190 g) and the resulting solution are mixed homogeneously. Cd(NO3)2·4H2O (1 mmol, 0.308 g) was dissolved in 20 mL water in a separate beaker. Then in a crystal tube 3 mL of Cd(II) solution was slowly and carefully layered with 6 mL of the above mentioned mixed-ligand solution using 2 mL of buffer solution in between the two solution, where the buffer solution was prepared using H2O and MeOH in equal volume (v/v ꞊ 1:1) in a separate beaker. The tube was sealed and kept undisturbed at room temperature. After 4 weeks white-colored block shaped single crystals suitable for X-ray diffraction, were obtained at the wall of the tube. The crystals were separated manually and washed with a methanol-water (1:1) mixture and dried under air (yield 70% based on metal). Anal. calc. for C15H28N4O8Cd: C, 35.69; H, 5.59; N, 11.10. Found: C, 35.73; H, 5.61, N, 11.22%. IR spectra (KBr pellet, 4000–400 cm−1): ν(O–H), 3440(stretch, H-bonded) ν(C–H, imidazole), 2936 (stretch); ν(C–H, alkane), 2861 (stretch) and 1400–1350 (bending); ν(C=C, imidazole), 1607–1400 (stretch); and ν(C–O), 1244 (stretch). {[Zn(1,4-bib)(glut)].(4H2O)}n (2). This compound has been synthesized by using the same slow diffusion technique of 1, but here Zn(NO3)2.6H2O (1mmol, 0.189g) has been used instead of Cd(NO3)2.4H2O (1mmol, .308g). White colored block shaped single crystals suitable for X-ray diffraction, were obtained after three weeks. The crystals were separated manually and washed with methanol-water (1:1) and dried under air (yield 76%). Anal. calc. for C15H28N4O8Zn: C, 39.35; H, 6.16; N, 12.24. Found: C, 39.41; H, 6.21, N, 12.22%. IR spectra (cm-1): IR spectra (KBr pellet, 4000–400 cm−1): ν(O–H), 3440 (stretch, H-bonded)

ν(C–H, imidazole), 2956

(stretch); ν(C–H, alkane), 2868 (stretch) and 1400–1350 (bending); ν(C=C, imidazole), 1607– 1400 (stretch); and ν(C–O), 1244 (stretch). {[Co(1,4-bib)( 3,5-pydc)].(2H2O)}n (3). The compound was synthesized previously42, 43 using a hydrothermal condition, but here we have synthesized this compound under mild conditions. The general protocol similar to that of the synthesis of 1 using pyridine-3,5-dicarboxylate (3,5-pydc) (1mmol, 0.209g) and Co(NO3)2.6H2O (1mmol, 0.291g) instead of glutarate (glut) (1mmol, 0.162 g) and Cd(NO3)2·4H2O (1 mmol, 0.308 g) has been utilized. Pink colored blocked shaped crystals suitable for X-ray diffraction analysis obtained after two weeks. The crystals were



separated manually and washed with methanol-water (1:1) and dried under air (yield 76%). Anal. calc. for C17H21N5O6Co: C, 45.34; H, 4.70; N, 15.55. Found: C, 45.31; H, 4.68, N, 15.59%. IR spectra (cm-1): ν(O–H), 3426(stretch, H-bonded); ν(C–H, Ar), 3136 (stretch); (C–H, imidazole), 2938 (stretch); ν(C–H, alkane), 2854 (stretch) and 1400–1350 (bending); ν(C=C, Ar), 1605–1366 (stretch); and ν(C–O), 1285 (stretch). {[Mn(1,4-bib)(3,5-pydc)].(2H2O)}n (4). This compound has been synthesized through the same procedure that used in synthesis of compound 3 using Mn(NO3)2.4H2O (1mmol, 0.251 g) instead of Co(NO3)3.6H2O (1mmol, 0.291g). After three weeks, white colored block shaped crystals suitable for X-ray analysis (yield 40%), were obtained at the wall of the tube. The crystals were separated manually and washed with methanol-water (1:1) and dried under air. Anal. calc. for C17H21N5O6Mn: C, 45.75; H, 4.74; N, 15.69. Found: C, 45.71; H, 4.67, N, 15.71%. IR spectra (cm-1): ν(O–H), 3491(stretch, H-bonded); ν(C–H, Ar), 3132 (stretch); (C–H, imidazole), 2946 (stretch); ν(C–H, alkane), 2856 (stretch) and 1400–1350 (bending); ν(C=C, Ar), 1618–1356 (stretch); and ν(C–O), 1283 (stretch). {[Zn(1,4-bib)(3-mglut)].(4H2O)}n (5). This has been synthesized by following the same slow diffusion procedure as for 1 using Zn(NO3)2·6H2O (1 mmol, 0.297 g) and disodium 3-methyl glutarate(3-mglut) (1 mmol, 0.146 g) instead of Cd(NO3)2·4H2O (1 mmol, 0.308 g) and disodium glutarate (Na2glut) (1 mmol, 0.162 g). Block shaped crystals suitable for X-ray diffraction analysis, were obtained after one month (yield 78%). The crystals were separated manually and washed with methanol-water (1:1) and dried under air. Anal. calc. for C16H30N4O8Zn: C, 40.73; H, 6.41; N, 11.87. Found: C, 40.71; H, 6.38, N, 11.71%. IR spectra (KBr pellet, 4000–400 cm−1): ν(O–H), 3442(stretch, H-bonded) ν(C–H, imidazole), 3137 (stretch); ν(C–H, alkane), 2944 (stretch) and 1402–1298 (bending); ν(C=C, imidazole), 1609–1400 (stretch); and ν(C–O), 1603 (stretch). {[Zn(1,4-bib)(2,2′-dmglut)].(2H2O)}n (6). The same procedure has been followed as that of synthesis of compound 5, but here disodium 2,2′-dimethyl glutarate (Na22,2′-dmglut) (1 mmol, 0.204 g) was used instead of disodium 3-methyl glutarate (3-mglut) (1 mmol, 0.146 g). White block shaped crystal suitable for X-Ray analysis, were obtained in 31% yield. The crystals were separated manually and washed with methanol-water (1:1) and dried in air. Anal. calc. for C17H28N4O6Zn: C, 45.39; H, 6.27; N, 12.46. Found: C, 45.35; H, 6.21, N, 12.57%. IR spectra (KBr pellet, 4000–400 cm−1): ν(O–H), 3426 (stretch, H-bonded) ν(C–H, imidazole), 2968


Page 6 of 30

Page 7 of 30 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(stretch); ν(C–H, alkane), 2854 (stretch) and 1400–1350 (bending); ν(C=C, imidazole), 1602– 1400 (stretch); and ν(C–O), 1244 (stretch). To get bulk amount, the compounds 1–6 have been synthesized in powder form mixing the corresponding solution of ligands and metal salt in water at their equal molar ratio. For all the compounds a precipitate appeared within 10 minutes of mixing and the solution is then stirred more for five hours. The compounds were filtered and separated after washing with small amount of 1:1 (v/v) methanol/water and dried in air. Compounds purity has been confirmed by PXRD, which give good resemblance between simulated and bulk-phase PXRD. The purity of the bulk sample was later confirmed by the results of elemental analysis and IR spectra as well, which is consistent with the structure obtained from the single crystals. Crystallographic Data Collection and Refinement Well separated crystals suitable for X-ray of compounds 1–6 were mounted on the tip of thin glass fibers with commercially available super glue. X-ray single crystal structural data of all six compounds were collected at room temperature on a Bruker APEX II diffractometer, equipped with a normal focus, sealed tube X-ray source with graphite monochromated Mo Kα radiation (k = 0.71073 Å). After the data collection the data were integrated using the SAINT45 program and the absorption corrections were made with SADABS46. All the structures were solved by SHELXS 201747 using the Patterson method and followed by successive Fourier and difference Fourier synthesis. Full matrix least-squares refinements were performed on F2 using SHELXL201747 with anisotropic displacement parameters for all non-hydrogen atoms. All the hydrogen atoms were located in appropriate position and fixed geometrically by the HFIX command. During refinement of compound 1 the lattice water molecule O2W was found to be disordered hence its occupancy was fixed at 0.5 before final refinement. All the calculations were carried out using SHELXS-2016/2017,47 SHELXL-2017,47 PLATON v1.15,48 WinGX system Ver1.80.39.49, TOPOS v3.250 and Mercury v3.0.51 Data collection and structure refinement parameters and crystallographic data for complexes 1, 2, 4–6 are given in Table 1. The selected bond lengths and angles are given in Tables S1, S3, S5, S7, S9. CCDC 1839475, 1839476, 1839478-1839480 contain the supplementary crystallographic data for this paper.



RESULT AND DISCUSSION Crystal structure descriptions of the CPs One of the reason behind the structural transformability comes from the fact that polycarboxylates can bind metal centers in different coordination mode. Here for our compounds different coordination modes for the dicarboxylates are shown in Scheme 2. The detail structural analysis for the compounds 1–6 are appended below.

Scheme 2. Different bridging modes of glutarate (glut2-) in 1 and 2, pyridine-3,5-dicarboxylate (3,5-pydc2-) in 3 and 4, 3-methyl glutarate (3-mglut2-) in 5 and 2,2′-dimethyl glutarate (2,2′dmglut2-) in 6: (a) bidentate-chelating mode in 1 (b) monodentate-chelating mode in 2 (c) monodentate- chelating mode in 3 (d) bidentate chelating mode in 4 (e) monodentate mode in 5 (f) monodentate mode in 6. {[Cd(1,4-bib)(glut)].2(H2O)}n (1). From Single crystal X-ray analysis, it has been found that compound 1 crystallizes in the monoclinic C2/c space group with Z value of 4 constructing a 2D architecture. The asymmetric unit of 1 contains one Cd(II) ion, half of 1,4-bib, half of glut2- and two lattice water molecules. The hexa coordinated Cd(II) centers form a distorted octahedral geometry with CdO4N2 coordination environment (Figure 1a). The four oxygen atoms (O1, O2, O1a, O2a) from two carboxylates group of two different glut ligands and two nitrogen atoms (N1 and N1a) from two different 1,4-bib ligands binds with Cd1 center to form the secondary building unit. The Cd−O bond lengths vary from 2.454(2) to 2.3081(19) Å, and both the Cd−N bond length is 2.247(2) Å (Table S1). Here, each glut2- ligand bridges with the two different Cd(II) centers in a bidentate-chealating fashion to form 1D chain along the crystallographic a


Page 8 of 30

Page 9 of 30 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


axis (Figure 1b). These 1D chains are further bridged by 1,4-bib in a criss-cross fashion (Figure 1c) to form a wavy 2D sheet along crystallographic ac plane (Figure 1d). The TOPOS50 analysis reveals that the structure of 1 can be represented as a 4-c uninodal net with Schläfli symbol of {44.62} (Figure 1e). Lattice water molecules are present in between such two 2D sheets (Figure S7)

and

involved

in

hydrogen-bonding

interactions

[O1W–H1WA...O2

and

O1W–

H1WB...O2WA], (Table S2) with carboxylato-oxygen atoms and extending the structure along crystallographic b axis resulting an overall supramolecular 3D structure.

Figure 1. (a) Atom labeling view of the coordination environment around hexa coordinated Cd(II) ion of compound 1; Zn (green), O (red), N (blue) and C (black). (b) One dimensional (1D) metal-carboxylate chain showing bis-chelated fashion of glutarate in 1 along a-axis, N, N'-donor 1,4-bib ligand is omitted for clarity. (c) One dimensional (1D) metal-N,N'-donor ligand in criscross fashion of compound 1 (d) View of the 2D structure of 1 pillared by the 1,4-bib ligand. (e) Simplified topological representation of the 4-connected uninodal 2D net in 1. {[Zn(1,4-bib)(glut)].4(H2O)}n (2). Compound 2 has similar structure as compound 1 although it crystallizes in the triclinic Pī space group with Z value of 2. The analysis of structure 2 shows the formation of a 2D sheet structure constructed by Zn(II) ion, glut2-, and 1,4-bib linker. The asymmetric unit of 2 contains same as 1 one metal center, Zn(II) ion, one 1,4-bib, one glut2differ only in the number of lattice water molecules. Here four lattice water molecules are



Page 10 of 30

present instead of two. The tetra coordinated Zn(II) center forms a distorted tetrahedral geometry a

with ZnO2N2 environment (Figures 2a). The two oxygen atoms (O1 and O4 ) from two different glut2- ligands and two different nitrogen atoms (N1 and N3) from two different 1,4-bib linkers are coordinated to Zn1 center. The Zn−O bond lengths are 1.9533(17) and 1.9899(15) Å and Zn−N bond lengths are 1.9985(18) and 2.0149(18) Å (Table S3). Here, each glut2- bridges with two different adjacent Zn(II) centers through bis-monodentate fashion to form a 1D metal carboxylate chain (Figure 2b) along the b-axis, and these 1D chains are further linked by the 1,4bib ligand to form a wavy 2D sheet in the bc plane (Figure 2c). Although both the 1 and 2 are formed with same building unit still there is some structural deviation which is possibly due to the size of the metal ion. Larger size Cd(II) ion binds to the carboxylate group in a chelating fashion whereas Zn(II) binds only one oxygen atoms of each carboxylate linker, which may have affected the orientation of the ligand and the final structure.

Figure 2. (a) View of coordination environment around tetra coordinated Zn(II) ion of compound 2; Zn (green), O (red), N (blue) and C (black). (b) One dimensional (1D) metalcarboxylate chain showing monodentate-chelate fashion of glutarate in 2 along a-axis, N,N'donor 1,4-bib ligand is omitted for clarity. (c) View of the 2D structure of 2 pillared by the 1,4bib ligand. (d) Simplified topological representation of the 4-connected uninodal 2D net in 2.


Page 11 of 30 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Topologically it is similar to that of 1, which is evident from the TOPOS50 analysis which reveals that this structure can be represented as a 4-connected uninodal net with corresponding Schläfli symbol of {44.62} (Figure 2d) exactly same as the compound 1. Here also the lattice water molecules reside inside two wavy sheets (Figure S8a) and connects those sheets by hydrogen bonding bc direction (O1W–H1WA...O3, O1W–H1WB...O4, O2W–H2WA...O1W, O2W–H2WB...O1W, O3W–H3WA...O1, O3W–H3WB...O4W, O4W–H4WA...O2, and O4W– H4WB...O3) (Table S4). These hydrogen bonding is responsible for the formation of supramolecular 3D architecture (Figure S8b).

{[Co(1,4-bib)( 3,5-pydc)].(2H2O)}n (3). The single crystal structure of this compound has been determined and found identical with reported compounds.42,43 In one of the reports42 the structure was described as distorted octahedral but in the other43 the same structure was mentioned as a distorted trigonal biyramidal. Actually, the penta-coordinated centre of Co(II) is forming a distorted square pyramidal structure here (Figure 3), with Addison parameter (tau) value of 0.38.52 Figures 3 and S3 are presented here for the sake of discussion, and to make a comparison with the other structure reported here. Here, 3,5-pydc2- bridges with two different adjacent Co(II) centers through bis-monodentate fashion and N-donor sight bind with another Co(II) ion to form a 2D metal carboxylate layer (Figure 3b) in the crystallographic ab plane. 1,4-bib binds to two adjacent Co(II) centre which are already connected by a carboxylate oxygen (O4) and nitrogen atom of a same 3,5-pydc2- ligand and thus 1,4-bib does not change the dimensionality of the overall framework (Figure 3c). The TOPOS50 analysis also reveals that the structure of 3 can be represented as a 3,5-connected binodal net with corresponding Schläfli symbol of {3.52}{32.53.64.7} (Figure 3d) as reported in the previously published structure.42 It is also interesting to note that due to the half rounded geometry of the 1,4-bib ligand there is a formation of vacant space in between the inter-layer space and this space is filled with lattice water molecules which has been stabilized by the hydrogen bonding with the carboxylate–oxygen atoms of the framework.(Figure S9a).



Figure 3. (a) View of coordination environment around penta coordinated Co(II) ion of compound 3; Zn (green), O (red), N (blue) and C (black). (b) One dimensional (1D) metalcarboxylate chain which forms 2D by ligation of N of acid with Co(II) metal ion in compound 3 along ab-axis, N,N'-donor 1,4-bib ligand is omitted for clarity. (c) Linkage of N,N' donor, 1,4bib to 2D metal carboxylate without changing dimension of 3 (d) Simplified topological representation of the 3,5 connected binodal 2D net in 3. {[Mn(1,4-bib)(3,5-pydc)].(2H2O)}n (4). Compound 4 crystallizes in monoclinic P21/n space group with Z value of 4 same as 3. Details structure analysis indicates that there is a formation of a two dimensional (2D) sheet structure like 3 with Mn(II) metal ions connected by 3,5-pydc2- and 1,4-bib linkers. Similar to that of 3 the asymmetric unit of 4 contains one metal center, Mn(II) ion, one 3,5-pydc2- ligand, one 1,4-bib ligand and two lattice water molecules though coordination and geometry are different from 3. The hepta-coordinated central Mn(II) ion takes up a distorted pentagonal bipyramidal geometry. In this geometry four oxygen atoms (O1, O2, O3a and O4a) from two different 3,5-pydc2- ligands and three nitrogen atoms (N1 and N4b) from two different 1,4-bib ligands and another nitrogen atom (N5c) from another different 3,5-pydc2ligand are coordinated to the metal ion (Figure 4a). The Mn–O bond lengths lie in the range 1.7587(19)–2.670(2) Å, while the Mn–N bond lengths are 2.211(2)–2.279(2) Å (Table S5). Here,

3,5-pydc2- bridges with three different adjacent Mn(II) centers where the carboxylates are


Page 12 of 30

Page 13 of 30 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


connected in chelating fashion and forms a 2D metal carboxylate layer (Figure 4b) in the abplane. 1,4-bib connects with two Mn(II) centers which are already connected by a 3,5-pydc2- and thus there is no enhancement of the dimentionality (Figure 4c). Geometrically 1,4-bib behave almost similar in both of 3 and 4 with a little difference. In case of Co(II) carboxylate bind in monodentate fashion but for Mn(II) carboxylate binds in chelating fashion. The TOPOS50 analysis reveals that the structure of 4 can be represented as a 3,5-connected binodal net same as compound 3 with corresponding Schläfli symbol of {3.52}{32.53.64.7} (Figure 4d). The intersheet distance is reduced here than compound 3 and it may be due to the coordination pattern of the carboxylates. Here the lattice water is present in between two adjacent 1,4-bib ligand (Figure S10a) and interconnected with hydrogen boding (O1W–H1WA...O1, O2W–H2WA...O2W and O2W–H2WB...O1W) (Table S6). These hydrogen bondings connect two adjacent sheets in c directions to make the overall structure as supramolecular 3D arrangement (Figure S10b).

Figure 4. (a) View of coordination environment around hepta coordinated Mn(II) ion of compound 4; one 1,4-bib and one 3,5-pydc are omitted for clarity, Zn (green), O (red), N (blue) and C (black). (b) One dimensional (1D) metal-carboxylate chain which forms 2D by the ligation of N of acid to Co(II) metal ion in compound 4 along ab-axis, N,N'-donor 1,4-bib ligand is omitted for clarity. (c) Linking of N,N' donor,1,4-bib to 2D metal carboxylate without changing dimension of 4 (d) Simplified topological representation of the 3,5 connected binodal 2D net in 4.



{[Zn(1,4-bib)(3-mglut)].(4H2O)}n (5). Compound 5 crystallizes in the triclinic Pī space group with Z value of 2. The structural analysis reveals the construction of a two dimensional (2D) wavy sheet structure with Zn(II) metal ions connected by 3-mglut2- and 1,4-bib linkers. There are one Zn(II) center, two half 1,4-bib ligands, one 3-mglut2- ligand and four lattice water molecules in the asymmetric unit. The tetra coordinated centre of Zn(II) with ZnO2N2 environment forms tetrahedral structure (Figure 5a). The two oxygen atoms (O1 and O3) from two different 3mglut2- ligands and two nitrogen atoms (N1 and N3) from two different 1,4-bib ligands are ligated to Zn(II) ion. The Zn−O bond lengths are 1.9629(19) and 1.9862(17) Å, and the Zn−N bond lengths are 1.999(2) and 2.008(2) Å (Table S7). Here 3-mglut2- binds in a bis-monodentate fashion with two different Zn(II) ions forming 1D metal carboxylate chain along a-axis (Figure 5b); which are further linked by 1,4-bib in same type of criss-cross fashion as the previous compounds to form a 2D wavy sheet in the crystallographic ac plane (Figure 5c).

Figure 5. (a) View of coordination environment around tetra coordinated Zn(II) ion of compound 5; Zn (green), O (red), N (blue) and C (black). (b) One dimensional (1D) metalcarboxylate chain showing monodentate-chelate fashion of 3-methyl glutarate in 5 along a- axis, N,N'-donor 1,4-bib ligand is omitted for clarity. (c) View of the 2D structure of 5 pillared by the 1,4-bib ligand. (d) Simplified topological representation of the 4-connected uninodal 2D net in 5.


Page 14 of 30

Page 15 of 30 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


The TOPOS50 analysis reveals that the structure of 5 can be represented as a 4-connected uninodal net with corresponding Schläfli symbol of {44.62}(Figure 5d). Lattice water molecules are resides in between the wavy sheets (Figure S11a) and involved in hydrogen bonding with the carboxylate oxygen atom (O1W–H1WA…O2W, O1W–H1WB…O3, O2W–H2WA…O1, O2W– H2WB…O3W,

O3W–H3WA…O4,

O3W–H3WB...O2,

O4W–H4WA...O1W,

O4W–

H4WB...O1W) (Table S8). These hydrogen bonding stabilizes the overall structure and extends the structure in ab direction to form an overall supramolecular 3D structure (Figure S11b). {[Zn(1,4-bib)(2,2′-dmglut)].(2H2O)}n (6). The single crystal X-ray diffraction study shows that compound 6 crystallizes in triclinic system with Pī space group having Z value of 2. Structural analysis shows the formation of wavy 2D sheet structure with Zn(II) ion connected by 2,2′dmglut2- and 1,4-bib linkers. The asymmetric unit of 6 is composed of one Zn(II) center, one 2,2′-dmglut2- ligand, one 1,4-bib ligand and two lattice water molecules. The Zn(II) center is four coordinated to form a distorted tetrahedral in the ZnO2N2 environment (Figure 6a). The two oxygen atoms (O2a and O4) from two different 2,2′-dmglut2- and two nitrogen atoms (N1 and N3) from two different 1,4-bib ligands are ligated to Zn1 center. The Zn−O bond lengths are 1.943(2) and 1.9667(17) Å and Zn−N bond lengths are 1.9961(19) and 2.0378(19) Å (Table S9). Here each 2,2′-dmglut2- binds with two different Zn(II) ion in a bis-monodentate fashion forming a 1D metal-carboxylate chain (Figure 6b) which are further linked by 1,4-bib linkers to form a wavy 2D sheet in the crystallographic bc plane (Figure 6c). The TOPOS50 analysis reveals that the structure of 6 can be represented as a 4-connected uninodal net with corresponding Schläfli symbol of {44.62}(Figure 6d). Here the lattice water molecules resides in between these sheets (Figure S12a) and participate in strong hydrogen bonding (O1W–H1WA...O1, O1W– H1WB...O2W, O2W−H2WA...O4, O2W−H2WB...O2W) (Table S10) which extends the structure along crystallographic a direction to form a supramolecular 3D structure (Figure S12b).



Figure 6. (a) View of coordination environment around tetra coordinated Zn(II) ion of compound 6; Zn (green), O (red), N (blue) and C (black). (b) One dimensional (1D) metalcarboxylate chain showing monodentate-chelate fashion of 2,2'-dimethyl glutarate in 6 along caxis, N,N'-donor 1,4-bib ligand is omitted for clarity. (c) View of the 2D structure of 6 pillared by the 1,4-bib ligand. (d) Simplified topological representation of the 4-connected uninodal 2D net in 6. Thermo Gravimetric Analysis (TGA) and Powder Diffraction (PXRD) Analysis Thermogravimetric Analysis (TGA) of compounds 1−6 were performed at the temperature range 30−600 °C with a flow rate of 10 cm3 min−1 and depicted in Figure S13. Compound 1 shows a weight loss of 14.06% (calcd, 14.32%) at temperature range 50−115 °C for four lattice water molecules. The dehydrated framework of compound 1 is stable up to 280 °C without showing any further weight loss; and after that it sharply decreases and collapses into unidentified products upon further heating. For compound 2, the weight loss has been observed as 15.14% (calcd. 15.73%) at 95 °C, which supports with the loss of four lattice water molecules started at 45 °C. After removal of all guest water molecules completely, the dehydrated framework shows stability up to 270 °C and afterwards collapses into unidentified products. Compound 3 shows weight loss of 7.57% (calcd. 7.99%) at 222 °C, indicating the loss of two guest water molecules which starts at 140 °C. The dehydrated framework is stable up to 324 °C showing no weight loss, and after that temperature, it sharply falls and decomposes into unidentified products.


Page 16 of 30

Page 17 of 30 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Figure 7. (a) Variable temperature powder X-ray diffraction for 1. (b) Powder X-ray diffraction patterns of compound 1 in different states, assynthesized compound heated at 150 oC and form 1′.

Figure 8. (a) Variable temperature powder X-ray diffraction for 2. (b, c) Powder X-ray diffraction patterns of compound 2 in different states, assynthesized compound heated at 150 oC and 250 oC and form 2′ and 2". In compound 4, the TGA curve shows weight loss 7.31% (calcd. 7.46%) at 204 °C, supporting the loss of two water molecules, which starts at 125 °C. The dehydrated framework is stable up to 350 °C and then forms unidentified products after that temperature. For compound 5 the weight loss is 15.15 % (calcd, 15.26 %), within the temperature range of 60−110 °C, which



corresponds to the release of four lattice water molecules, and the dehydrated framework found stable up to 320 °C without showing any further weight loss, and finally collapses into unidentified products during further heating above 320 °C. Compound 6 loses its single crystallinity at room temperature owing to quick release of lattice water, the dehydrated compound is stable up to 295 °C and after that temperature the compound decomposes into unidentified products. Air dried powdered compounds, except 6, are used to measure the powder X-ray diffractions (PXRD) at room temperature. As TGA shows compound 6 loses its lattice water at the room temperature, PXRD of this compound is performed with the addition of little mother solvent. Homogeneity between the experimental patterns and their respective simulated patterns confirms the bulk purity of all the compounds (Figure 7b, 8b, 9b, 10b, 11b, 12b).

Figure 9. (a) Variable temperature powder X-ray diffraction for 3. (b, c) Powder X-ray diffraction patterns of compound 3 in different states, assynthesized compound heated at 150 oC and 230 oC and form 3′ and 3".


Page 18 of 30

Page 19 of 30 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Figure 10. (a) Variable temperature powder X-ray diffraction for 4. (b, c) Powder X-ray diffraction patterns of compound 4 in different states, assynthesized compound heated at 230 oC and 280 oC and form 4′ and 4".

Figure 11. (a) Variable temperature powder X-ray diffraction for 5. (b, c) Powder X-ray diffraction patterns of compound 5 in different states, assynthesized compound heated at 150oC and 250 oC and form 5′ and 5".



Figure 12. (a) Variable temperature powder X-ray diffraction for 6. (b) Powder X-ray diffraction patterns of compound 6 in different states, assynthesized compound at room temperature form 6′. Structural transformation and reversibility In order to investigate the thermal stability, in situ variable temperature powder X-ray diffraction (VTPXRD) experiment of all the compounds 1-6 were done in the temperature range of 30 o

C−250 oC for compounds 1, 2, 5, 6 and 30 oC to 280 oC for compound 3 and 4. For this

experiment, powdered samples were kept in the non-ambient attachment of the instrument and heated at a rate of 1 °C/s. At the required temperature, data were taken. VTPXRD of all six compounds shows considerable changes in the powder patterns (Figures 7a−12a), upon heating. All over the range of temperature there is retention of crystallinity with peak shifting, new peak appearing and peak disappearing is observed; which confirms crystalline to crystalline phase transformation. All the compounds show two steps crystalline to crystalline phase transformation except compounds 1 and 6 which show single step transformation. In the aforesaid case, the first transformation may be due to removal of solvent molecules and second transformation occurs due to attaining high thermal energy in dehydrated framework. For compound 1 it is clear that the diffraction patterns below 50 °C remained almost unchanged, indicating the retention of the crystal lattice but at 80 oC diffraction pattern changes with generation of new peaks (Figure 7a) and afterwards there is no change in pattern any more. For compound 2 the first structural transformation starts after 30 oC and the framework found stable up to 200 oC and after that temperature again a new structural transformation occurs (Figure 8a). Compound 3 retains its crystallinity up to 70 oC and above 70 oC structural transformation starts which is stable up to 190 oC and again near about 230 oC the second transformation starts (Figure 9a). For compound


Page 20 of 30

Page 21 of 30 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


4 the first structural transformation occurs at 180 oC possibly due to the loss of lattice water molecule and another transformation occurs at 280 oC (Figure 10a). For compound 5 the first transformation occurs at 60 oC may be due to phase transformation for loosing lattice water molecules and another occurs at 250 oC (Figure 11a). For compound 6 phase transformation starts at 30 oC which is due to instant release of lattice water molecule which is also supported by TGA (Figure 12a). To get the structural insight of the transformed phases, compounds are heated in their respective transformation temperature for 2h and with these isolated transformed products, PXRD experiment has been performed (Table S11-S20, Figure S14-S23). Indexing of the PXRD patterns of first transformed product for 1−6 (referred to as 1′−6′ respectively) using the TREOR program53 suggests a structural expansion in case of all the compounds except compound 3′ where the cell volume is almost remain same after transformation. The indexing of PXRD patterns for the second transformed products for 2−5 (referred to as 2′′−5′′ respectively) (Figure S16, S18, S20, S22) show the structural contraction in all cases except in 3′′ where structural expansion occurs. Details study of indexing suggest that in case of 2′ expansion of 194% along a and b axes whereas for 2′′ shrinkage of 49.25% occurred along a and b axes with respect to 2′ (Figure S15, S16 Table S12, S13). In case of 3′′ expansion of 34.22% occurred along b and c axes with respect to 3′ (Figure S18, Table S15). For compound 4′, 5′, 6′ expansion of 28.52%, 115.89% and 161.66% observed along a and b axes (Figure S19, S21, S23, Table S16, S18, S20) and for 4′′ and 5′′ shrinkage of 55.94% and 20.66% observed along a, b and a axes (Figure S20, S22 and Table S17, S19) with respect to 4′ and 5′. Details of the indexing results, transformed cells and Le Bail fitting plot are provided in Table S11−S20 and Figure S14−S23. To study the structural reversibility of the transformed products, they were dipped afterwards in the respective mother-liquor like water-methanol, dry methanol and water; as the case may be, for 1 day. For all of these solvents, compounds 2′, 2′′, 3′, 3′′, 4′, 4′′ revert back to their initial assynthesized product (Figure 8b and c,9b and c,10b and c). All of these transformations may have taken place by the act of the water. Although, dry methanol contents no water, for these water sensible compounds, environmental traces of water may have done the job. Compound 1′, 5′ and 5′′ return back to as-synthesized product in water-methanol and water but unable to revert back in dry methanol (Figure 7b, 11b and c) and compound 6′ do not come back to as-synthesized



product in any of the above mentioned solvent (Figure 12b). All of these transformations are analyzed and confirmed by the PXRD study. IR spectroscopic studies also are in good agreement with the above mentioned results (Figure S1−S6). After transformation peak broadening, especially in the carbonyl group region, has been observed which suggest there is a change in ligand environment around metal center after the corresponding transformation. These changes in spectra returns as initial after the soaking in the solvent as mentioned. Here all of these compounds 1-6 contain N, N'-donor linker 1,4-bib which is inherently flexible in nature due to presence of butane linkage, having low energy transformable conformers. Due to this flexible nature of 1,4-bib all the compounds is expected to show ligand induced flexibility hence, phase transformations. As the energy barrier of these transformations are low, thus on removal of lattice water molecules by heating, they can transform to another phase which again revert back to their initial phase in presence of water. This understanding could be pretty justified for the reason behind the reversible transformation in the structure 1-5, but in case of 6 the phenomena is slightly different. This compound shows irreversible transformation although both 5 and 6 contains Zn(II) metal ion and 1,4-bib ligand. They have been synthesized in a same way and structurally also very similar. But the major difference resides in the dicarboxylates in their structure, as they are with different derivative of same carboxylate, glutarate; 3-methyl glutarate (in 5) and 2, 2'-dimethyl glutarate (in 6). There is an extra methyl group in the dicarboxylate linker in 6 and this hydrophobic extra methyl group may be incommode the incoming water molecules which is required to regain the mother structure in 6. This water resistant nature may be preventing to get back the mother structure in 6, as inclusion of water is the primary factor toward the reversibility of the transformed phase. Adsorption Studies To evaluate the porosity and adsorption properties of compounds 1−6, the N2 and CO2 gas adsorption measurement of the corresponding dehydrated samples 1′−6′ were done. The N2 adsorption was carried out at 77K and that exhibit type-II isotherms suggesting only surface adsorption for 1, and in all other cases the compounds are showing negligible N2 adsorption suggesting nonporous nature of the compounds towards N2 (Figure S25). The CO2 adsorption study was performed at 195K for all the desolvated compounds. The compounds 2′, 4′ and 6′ gave reversible isotherm with uptake of 30·4 cm3 g-1 (5·97 wt %), 26·89 cm3 g-1 (5·28 wt%) and 26·80 cm3 g−1 (5·26wt%) at 1 bar indicating the microporous nature of the compounds (Figure


Page 22 of 30

Page 23 of 30 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


S24). The CO2 sorption isotherms of these three compounds exhibit hysteresis40,41 possibly due to some kinetic trapping of CO2 by the framework. In all other cases there are negligible CO2 adsorption suggesting nonporous nature of the framework even towards CO2. CONCLUSION Here we have described the synthesis and characterization of five metal-organic frameworks of different divalent transition metal ions from 3,5-pydc, Na2glut, 3-mglut, Na22,2′-dmglut and 1,4bib ligands. We have studied the structural dynamicity of these compounds along with a previously published compound and found all of these have crystalline to crystalline structural transformability upon heating. The transformation are found in single step in some cases and even they are multistep in nature in some instances. It is needless to mention that the interesting feature lies in their reversibility on soaking in certain solvent systems. The transformed phases are meticulously characterized by variable temperature PXRD study. The understanding of such transformation and their study may open the pathways of the preparation of some temperature mediated materials, which are not being possible to synthesize in conventional reaction method. Each of these phases may be a representative of some certain applications and with this knowledge, it can be able to achieve some multi-purpose materials; just by heating them in suitable different temperature. An extensive application related study for each phase of such transformable materials may lead to the making of multi-functional MOF based smart materials in near future. ASSOCIATED CONTENT Supporting Information The figures related to IR, UV-Vis spectral study; PXRD patterns, and TGA of compounds along with different structural figures and tables related to the crystal structures reported in this paper are available as SI. CCDC 1839475, 1839476 and 1839478-1839480 contains the supplementary crystallographic data for this paper in CIF format. AUTHOR INFORMATION Corresponding Author E–mail: [email protected], FAX: +9133 2414 6223 Notes: The authors declare no competing financial interest.



ACKNOWLEDGMENTS DG gratefully acknowledges the financial assistance given by SERB (SB/S1/IC-06/2014). FH and AH acknowledges UGC and CSIR respectively, for their research fellowship.

REFERENCES 1. Wang, C.; Zheng, M.; Lin W. Asymmetric Catalysis with Chiral Porous Metal–Organic Frameworks: Critical Issues. J. Phys. Chem. Lett. 2011, 2, 1701–1709. 2. Bhattacharya, B.; Maity, D. K.; Pachfule, P.; Colacio, E.; Ghoshal, D. Syntheses, X-ray structures, catalytic activity and magnetic properties of two new coordination polymers of Co(II) and Ni(II) based on benzenedicarboxylate and linear N,N’-donor Schiff base linkers. Inorg. Chem. Front. 2014, 1, 414−425. 3. Bhattacharjee, S.; Khan, M. I.; Li, X.; Zhu Q. L.; Wu X. T. Recent Progress in Asymmetric Catalysis and Chromatographic Separation by Chiral Metal–Organic Frameworks. Catalysts 2018, 8, 120. 4. Gole, B.; Bar, A. K.; Mallick, A.; Banerjee, R.; Mukherjee, P. S. An electron rich porous extended framework as a heterogeneous catalyst for Diels–Alder reactions. Chem. Commun. 2013, 49, 7439−7441. 5. Jayaramulu, K.; Reddy, S. K.; Hazra, A.; Balasubramanian, S.; Maji, T. K. Three-Dimensional Metal–Organic Framework with Highly Polar Pore Surface: H2 and CO2 Storage Characteristics. Inorg. Chem. 2012, 51, 7103−7111. 6. Maity, D. K.; Halder, A.; Pahari, G.; Haque, F.; Ghoshal, D. Hydrogen Uptake by an Inclined Polycatenated Dynamic Metal–Organic Framework Based Material. Inorg. Chem. 2017, 56, 713−716. 7. Mallick, A.; Saha, S.; Pachfule, P.; Roy, S.; Banerjee, R. Selective CO2 and H2 adsorption in a chiral magnesium-based metal organic framework (Mg-MOF) with open metal sites. Journal of Materials Chemistry 2010, 20, 9073−9080. 8. Chen, B.; Ma, S.; Hurtado, E. J.; Lobkovsky, E. B.; Liang, C.; Zhu, H.; Dai, S. Selective Gas Sorption within a Dynamic Metal-Organic Framework. Inorg. Chem. 2007, 46, 8705–8709. 9. Tripuramallu, B. K.; Manna, P.; Reddy, S. N.; Das, S. K. Factors Affecting the Conformational Modulation of Flexible Ligands in the Self-Assembly Process of Coordination Polymers: Synthesis, Structural Characterization, Magnetic Properties, and Theoretical Studies


Page 24 of 30

Page 25 of 30 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


of

[Co(pda)(bix)]n,

OH)(pda)(ptz)]n·nH2O,

[Ni(pda)(bix)(H2O)]n, [Co(hfipbb)(bix)0.5]n,

[Cu(pda)(bix)2(H2O)2]n·8nH2O, and

[Co(2,6-pydc)(bix)1.5]n·4nH2O.

[Co2(µCryst.

Growth Des. 2012, 12, 777−792. 10. Bhattacharya, B.; Maity, D. K.; Mondal, R.; Colacio, E.; Ghoshal, D. Two Series of Isostructural Coordination Polymers with Isomeric Benzenedicarboxylates and Different Azine Based N,N′-Donor Ligands: Syntheses, Characterization and Magnetic Properties. Cryst. Growth Des. 2015, 15, 4427−4437. 11. Goswami, S.; Adhikary, A.; Jena, H. S.; Biswas, S.; Konar, S. A 3D Iron(II)-Based MOF with Squashed Cuboctahedral Nanoscopic Cages Showing Spin-Canted Long-Range Antiferromagnetic Ordering. Inorg. Chem. 2013, 52, 12064−12069. 12. Lama, P.; Aijaz, A.; Sañudo, E. C.; Bharadwaj, P. K. Synthesis, Structure, and Magnetic Properties of Cobalt(II) Coordination Polymers from a New Tripodal Carboxylate Ligand: Weak Ferromagnetism and Metamagnetism. Cryst. Growth Des. 2010, 10, 283−290. 13. Lustig, W. P.; Mukherjee, S.; Rudd, N. D.; Desai, A. V.; Li, J.; Ghosh, S. K. Metal–organic frameworks: functional luminescent and photonic materials for sensing applications. Chem. Soc. Rev. 2017, 46, 3242–3285. 14. Bhattacharya, B.; Halder, A.; Paul, L.; Chakrabarti, S.; Ghoshal, D. Eye‐Catching Dual‐Fluorescent Dynamic Metal–Organic Framework Senses Traces of Water: Experimental Findings and Theoretical Correlation. Chem. – Eur. J. 2016, 22, 14998−15005. 15. Hu, Z.; Deibert, B. J.; Li, J. Luminescent metal–organic frameworks for chemical sensing and explosive detection. Chem. Soc. Rev. 2014, 43, 5815−5840. 16. Dey, A.; Konavarapu, S. K.; Sasmal, H. S.; Biradha, K. Porous Coordination Polymers Containing Pyridine-3,5-Bis(5-azabenzimidazole): Exploration of Water Sorption, Selective Dye Adsorption, and Luminescent Properties. Cryst. Growth Des. 2016, 16, 5976–5984. 17. Li, B.; Wen, H. M.; Cui, Y.; Zhou, W.; Qian, G.; Chen, B. Emerging Multifunctional Metal– Organic Framework Materials. Adv. Mater. 2016, 28, 8819–8860. 18. Kaur, H.; Venkateswarulu, M.; Kumar, S.; Krishnana, V.; Koner, R. R. A metal–organic framework based multifunctional catalytic platform for organic transformation and environmental remediation. Dalton Trans. 2018, 47, 1488–1497. 19. Teplensky, M. H.; Fantham, M.; Li, P.; Wang, T. C.; Mehta, J. P.; Young, L. J.; Moghadam, P. Z.; Hupp, J. T.; Farha, O. K.; Kaminski, C. F.; Fairen-Jimenez, D. Temperature Treatment of



Highly Porous Zirconium-Containing Metal–Organic Frameworks Extends Drug Delivery Release. J. Am. Chem. Soc. 2017, 139, 7522–7532. 20. Li, H. Hill, M. R. Low-Energy CO2 Release from Metal–Organic Frameworks Triggered by External Stimuli. Acc. Chem. Res. 2017, 50, 778–786. 21. Graham, A. J.; Allan, D. R.; Muszkiewics, A.; Morrison, C. A.; Moggach, S. A. The Effect of High Pressure on MOF-5: Guest-Induced Modification of Pore Size and Content at High Pressure. Angew. Chem. Int. Ed. 2011, 50, 11138–11141. 22. Fernandez, C. A.; Martin, P. C.; Schaef, T.; Bowden, M. E.; Thallapally, P. K.; Dang, L.; Xu, W.; Chen, X. McGrail, B. P. An Electrically Switchable Metal-Organic Framework. Sci. Rep. 2014, 4, 6114. 23. Pal, A.; Lin, J. -B.; Chand, S.; Das, M. C. A 3D Microporous MOF with mab Topology for Selective CO2 Adsorption and Separation. ChemistrySelect 2018, 3, 917–921. 24. Jiang, K.; Zhang, L.; Hu, Q.; Zhao, D.; Xia, T. F.; Lin, W. X.; Yang, Y. Y.; Cui, Y. J.; Yang, Y.; Qian, G. D. Pressure controlled drug release in a Zr-cluster-based MOF. J. Mater. Chem. B 2016, 4, 6398−6401. 25. Wu, J.; Xu, J. W.; Liu, W. C.; Yang, S. Z.; Luo, M. M.; Han, Y. Y.; Liu, J. Q. Batten, S. R. Designed metal–organic framework based on metal–organic polyhedron: Drug delivery. Inorg. Chem. Commun. 2016, 71, 32−34. 26. Zhu, X.; Zhao, J. -W.; Li, B. –L.; Song, Y.; Zhang, Y. –M.; Zhang, Y. A Two-Dimensional Metal-Organic Framework Based on a Ferromagnetic Pentanuclear Copper(II). Inorg. Chem. 2010, 49, 1266–1270. 27. Prasad, T. K.; Suh, M. P. Control of Interpenetration and Gas-Sorption Properties of Metal– Organic Frameworks by a Simple Change in Ligand Design. Chem. Eur. J. 2012, 18, 8673– 8680. 28. Xu, H.; Chen, R.; Sun, Q.; Lai, W.; Su, Q.; Huang, W.; Liu, X. Recent progress in metal– organic complexes for optoelectronic applications. Chem. Soc. Rev. 2014, 43, 3259–3302. 29. Mura, S.; Nicolas, J.; Couvreur, P. Stimuli-responsive nanocarriers for drug delivery. Nat. Mater. 2013, 12, 991−1003. 30. Kundu, P. K.; Olsen, G. L.; Kiss, V.; Klajn, R. Nanoporous frameworks exhibiting multiple stimuli responsiveness. Nat. Commun. 2014, 5, 3588.


Page 26 of 30

Page 27 of 30 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


31. Irie, M.; Fukaminato, T.; Matsuda, K.; Kobatake, S. Photochromism of Diarylethene Molecules and Crystals: Memories, Switches, and Actuators. Chem. Rev. 2014, 114, 12174−12277. 32. Easun, T. L.; Moreau, F.; Yan, Y.; Yang, S.; der, M. S. Structural and dynamic studies of substrate binding in porous metal–organic frameworks. Chem. Soc. Rev. 2017, 46, 239−274. 33. Dybtsev, D. N.; Chun, H.; Kim, K. Rigid and Flexible: A Highly Porous Metal–Organic Framework with Unusual Guest-Dependent Dynamic Behavior. Angew. Chem. Int. Ed. 2004, 43, 5033–5036. 34. Schneemann, A.; Bon, V.; Schwedler, I.; Senkovska, I.; Kaskel, S.; Fischer, R. A. Flexible metal–organic frameworks. Chem. Soc. Rev. 2014, 43, 6062−6096. 35. Horike, S.; Shimomura, S.; Kitagawa, S. Soft porous crystals. Nat. Chem. 2009, 1, 695−704. 36. Mendes, R. F.; Paz, F. A. A. Transforming metal–organic frameworks into functional materials. Inorg. Chem. Front. 2015, 2, 495–509. 37. Shigematsu, A.; Yamada, T.; Kitagawa, H. Selective Separation of Water, Methanol, and Ethanol by a Porous Coordination Polymer Built with a Flexible Tetrahe. J. Am. Chem. Soc. 2012, 134, 13145−13147. 38. Spencer, E.; Kiran, M. S. R. N.; Li, W.; Ramamurty, U.; Ross, N. L.; Cheetham, A. K. Pressure-Induced Bond Rearrangement and Reversible Phase Transformation in a Metal– Organic Framework. Angew. Chem. Int. Ed. 2014, 53, 5583−5586. 39. Halder, A.; Ghoshal, D. Structure and properties of dynamic metal–organic frameworks: a brief accounts of crystalline-to-crystalline and crystalline-to-amorphous transformations CrystEngComm 2018, 20, 1322−1345. 40. Bhattacharya, B.; Halder, A.; Maity, D. K.; Ghoshal, D. Dynamic metal–organic frameworks: syntheses,

characterizations,

sorption

studies

and

their

hydrolytic

inter-conversion.

CrystEngComm 2016, 18, 4074–4083. 41. Halder, A.; Bhattacharya, B.; Dey, R.; Maity, D. K.; Ghoshal, D. Reversible Phase Transformation in Three Dynamic Mixed-Ligand Metal–Organic Frameworks: Synthesis, Structure, and Sorption Study. Cryst. Growth Des. 2016, 16, 4783-4792. 42. Lv, Y.; Qi, Y.; Sun, L.; Luo, F.; Che, Y.; Zheng, J. Construction of Metal-Organic Frameworks with the Pyridine-3,5-dicarboxylate Anion and Bis(imidazole) Ligands: Synthesis, Structure, and Thermostability Studies. Eur. J. Inorg. Chem. 2010, 5592–5596.



43. Qu, H.; Qiu, L.; Leng, X.-K.; Wang, M.-M.; Lan, S.-M.; Wen , L.-L.; Li, D.-F. Structures and photocatalytic activities of metal-organic frameworks derived from rigid aromatic dicarboxylate acids and flexible imidazole-based linkers. Inorg. Chem. Commun. 2011, 14, 1347–1351. 44. Li, C.; Zhao, L.; Li, J.; Ding, X.; Chen, S.; Zhang, Q.; Yub, Y.; Jia, X. Self-assembly of [2]pseudorotaxanes based on pillar[5]arene and bis(imidazolium) cations. Chem. Commun. 2010, 46, 9016–9018. 45. SMART (V 5.628), SAINT (V 6.45a), XPREP, SHELXTL, Bruker AXS Inc. Madison, WI, 2004. 46. Sheldrick, G. M. SADABS (Version 2.03), University of Göttingen, Germany, 2002. 47. Sheldrick, G. M. Crystal structure refinement with SHELXL. Acta Crystallogr. Sect. C: Struct. Chem. 2015, 71, 3. 48. Spek, A. L. Structure validation in chemical crystallography. Acta Crystallogr., Sect. D: Biol. Crystallogr. 2009, 65, 148. 49. Farrugia, L. J. WinGX, WinGX suite for small-molecule single-crystal crystallography. J. Appl. Crystallogr. 1999, 32, 837. 50. Blatov, V. A.; Shevchenko, A. P.; Serezhkin, V. N. TOPOS3.2: a new version of the program package for multipurpose crystal-chemical analysis. J. Appl. Crystallogr. 2000, 33, 1193. 51. Macrae, C. F.; Edgington, P. R.; McCabe, P.; Pidcock, E.; Shields, G. P.; Taylor, R.; Towler, M.; van de Streek, J. Mercury: visualization and analysis of crystal structures. J. Appl. Cryst. 2006, 39, 453-457. 52. Addison, A. W.; Rao, T. N.; Reedijk, J.; van Rijn, J.; Verschoor, G. C. Synthesis, structure, and spectroscopic properties of copper(II) compounds containing nitrogen–sulphur donor ligands; the crystal and molecular structure of aqua[1,7-bis(N-methylbenzimidazol-2′-yl)-2,6dithiaheptane]copper(II) perchlorate. J. Chem. Soc. Dalton Trans. 1984, 1349–1356. 53. Warner, P. E.; Erikson, L.; Westdahl, M. TREOR, a semi-exhaustive trial-and-error powder indexing program for all symmetries. J. Appl. Crystallogr. 1985, 18, 367–370.


Page 28 of 30

Page 29 of 30 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Table 1. Crystallographic and Structural Refinement Parameters for Complexes 1, 2, 4-6. 1

2

4

5

6

formula

C15H28N4O8Cd

C15H28N4O8Zn

C17H21N5O6Mn

C16H30N4O8Zn

C17H28N4O6Zn

formula weight

502.806

457.80

482.36

471.83

449.82

crystal system

monoclinic

triclinic

monoclinic

triclinic

triclinic

space group

C2/c

Pī

P21/n

Pī

Pī

a/ Å

9.5365(3)

8.4154(2)

9.868(5)

8.5177(3)

8.2612(2)

b/Å

14.6398(3)

8.6294(2)

12.450(5)

8.8546(3)

8.5236(2)

c/ Å

15.9057(3)

16.5502(4)

16.518(5)

15.9351(6)

15.4406(4)

α/°

90

94.818(1)

90

94.306(2)

80.567(2)

β/°

100.812(1)

104.057(1)

97.597(5)

98.816(2)

89.201(2)

γ/°

90

110.031(1)

90

112.073(2)

85.325(2)

V/ Å3

2389.1(16)

1076.77(5)

2011.5(14)

1088.98(7)

1068.98(5)

4

2

4

2

2

1.525

1.412

1.474

1.439

1.398

µ /mm

1.046

1.187

0.700

1.176

1.187

F(000)

1016

480

924

496

472

θ range/°

2.6, 27.5

1.3, 27.6

2.1, 27.6

1.3, 27.5

2.4, 27.5

reflections collected 18437

17744

34018

16261

18687

unique reflections

2497

4956

4638

4994

4893

reflections I > 2σ(I)

2312

4272

4019

3520

4146

Rint

0.024

0.031

0.031

0.052

0.026

1.05

1.04

1.03

1.00

0.0259

0.0343

0.0381

0.0479

0.0394

wR2(I > 2σ(I))[a]

0.0672

0.0875

0.1060

0.0970

0.1161

∆ρ min / max /e Å3

-0.28, 0.44

-0.33, 1.00

-0.60, 0.63

-0.39, 0.60

-0.41, 0.68

Z –3

Dc/ g cm –1

goodness-of-fit (F2) 1.07 R1 (I > 2σ(I))

[a]

R1 = ΣFo–Fc/ΣFo, wR2 = [Σ (w (Fo 2 – Fc2 ) 2 )/ Σw (Fo 2 )2] ½

[a]



Table of Contents Crystalline to Crystalline Phase Transformations in Six Two Dimensional Dynamic Metal-Organic Frameworks: Syntheses, Characterizations and Sorption Studies Fazle Haque, Arijit Halder and Debajyoti Ghoshal*

Dynamic metal-organic frameworks showing single step or multistep structural transformation upon desolvation.


Page 30 of 30

Crystalline to Crystalline Phase Transformations in Six Two

Recommend Documents