Light and Heat Dually Responsive Luminescence in Organic

Subscriber access provided by University of Newcastle, Australia

Article

Light and Heat Dually Responded Luminescence in Organic Templated CdSO4-type Halogeno(cyano)cuprates with Site-Substituted Disorder of Halogenide/Cyanide Shi-Li Li, Jie Wang, Fu-Qiang Zhang, and Xian-Ming Zhang Cryst. Growth Des., Just Accepted Manuscript • DOI: 10.1021/acs.cgd.6b01598 • Publication Date (Web): 09 Jan 2017 Downloaded from http://pubs.acs.org on January 10, 2017

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 free 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 accessible to all readers and 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.

Crystal Growth & Design 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 25

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

Light and Heat Dually Responded Luminescence in

Organic

Templated

Halogeno(cyano)cuprates

with

CdSO4-type Disorder

of

Halogenide/Cyanide Shi-Li Li†, Jie Wang†, Fu-Qiang Zhang†, Xian-Ming Zhang†‡* †

School of Chemistry & Material Science, Shanxi Normal University, Linfen 041004, P. R.

China ‡

Institute of Crystalline Materials, Shanxi University, Taiyuan 030006 P. R. China

KEYWORDS: tunable photoluminescence; thermochromic luminescence; isostructural; halogeno(cyano)cuprate

ABSTRACT: The light and heat dually sensitive luminescent materials have promising applications such as LEDs, bioimaging and memories but are rather scarce due to simultaneous requirements of stimuli induced structural flexibility and existence of multiple emissions. In continuation of our research interest in tunable photoluminescent materials with templated organic-ligand, we report herein two isostructural organic templated CdSO4-topological halogeno(cyano)cuprates with site-substitued disorder of halogenide and cyanide, formulated as [Me2DABCO]2Cu4Br5(CN)3 (1) and [Me2DABCO]2Cu4I4.5(CN)3.5 (2) (Me2DABCO = N,N’-dimethyl-1,4-diazabicyclo[2.2.2]octane). Both 1 and 2 show a very strong emission

ACS Paragon Plus Environment

1


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 25

band upon photoexitation with microsecond lifetime and high quantum yield. With the increase of excitation wavelength, the strong main emission band in 1 is gradually red-shifted from 495 nm to 535 nm, seemingly breaking Kasha’s rule, and the strong main emission in 2 also significantly red-shift. With the decrease of temperature, the low energy emission in 1 also is red-shifted, while this phenomenon is not found in 2. The photochromic luminescence for 1 and 2 might be caused by multiple emission centers associated with disorder of halogenide and cyanide.

INTRODUCTION: Tunable photoluminescent materials, exhibiting reversible modification of the emission wavelength in response to external environments (e.g., light, pH values, solvent, temperature, mechanical force or electric and magnetic fields), have gained considerable interest for their potential technological applications in light emitting devices (LEDs), bioimaging, sensing, detection, memories, optical display devices and so on.1−3 To date, most tunable luminescent materials only respond to a single stimulus.4−5 Comparatively speaking, multi-stimuli-responsive luminescent materials have more significant practical applications on account of the diverse and complicated external environments.6 In the previous research, a tiny minority of organic molecules, organic polymers and discrete metal complexes have the character of multi-stimuli-responsive luminescence, which are mainly concentrated on responding to temperature, mechanical force, vapor and solvent.7−10 As is well known, light and heat are the major stimuli in the natural environment, so it is more valuable to explore photochromic and thermochromic luminescent materials that are sensitive to the dual stimuli. However, these dual-stimuli sensitive materials are very difficult to obtain,11 because it should be simultaneously


2

Page 3 of 25

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


satisfied to the following criteria: (a) the structural geometries are easily distorted with the varied temperature, accompanied by the change of weaker interaction such as metallophilic interactions, hydrogen bond, packing interaction and other intramolecular weak interacitions;12−14 (b) these materials should perform multiple emissions with different excitation wavelengths, induced mainly by multi-metal center, multi-component, the size effect or defect states.15−18 Thus, the rational design and synthesis of the light and heat dual-stimuli-responsive luminescent materials remains highly challenging. To pursue this new type of dual-stimuli-responsive materials, it is found that copper halide hybrids might be the potential candidates via a detailed investigation, which is issued for several different reasons as follows: (1) the structural geometries of copper halide clusters are considerable flexibility, leading to easy distortion upon external stimulus;19−21 (2) the minor distinction between isomorphic copper halide clusters can give rise to a large variation of the luminescent properties;22 (3) Solid solutions can be generated in copper halide-based materials via substitution of adjacent halogen elements and result in different clustered aggregates,23 which might play a key role in forming the independent isolated emission centers.24 In our previous report, copper halide solid solutions can be remarkably formed via substitution of H for Cu due to equivalent functionality of H in X–H⋅⋅⋅Y and Cu(I) in X–Cu–Y bonds.25 While substitution elements in solid solutions are adjacent on the periodic table in common, and their functional properties are very similar. Additionally, it is well known that the coordination abilities of pseudo-halides such as CN– are nearly the same as that of halides, which provides an opportunity to disordered occupancy of halide and cyanide in halogenocuprate materials and obtain expected solid solutions. Inspired by the above-mentioned opinions and our


3


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 4 of 25

previous works, we aimed to synthesize halogenocuprate solid solutions with dualstimuli-responsive luminescent properties via disordered occupancy of halide and CN– groups. Fortunately, we have synthesized two isostructural copper halide-based solid solutions with CdSO4-type framework involving disorder of halogenide and cyanide, namely, [Me2DABCO]2Cu4Br5(CN)3 (1) and [Me2DABCO]2Cu4I4.5(CN)3.5 (2). Due to disordered occupancy of halogenide/cyanide sites in these two isostructral solid solutions, the chemical compositions of 1 and [Me2DABCO]Cu2Br3(CN)

to

2 can be also described as 1:1 of

[Me2DABCO]Cu2Br2(CN)2,

and

1:3

of

[Me2DABCO]Cu2I3(CN) to [Me2DABCO]Cu2I2(CN)2, respectively. 1 exhibits interesting tunable photoluminescence upon varying the temperature and excitation light as expected, while 2 is only sensitive to light-stimuli. EXPERIMENTAL SECTION Materials and Methods. All reagents and solvents were obtained commercially and used without further purification. The FT-IR spectra in range 400-4000 cm–1 were obtained on a Perkin-Elmer Spectrum BX FTIR spectrometer using KBr disks. X-ray powder diffraction (XRPD) data were recorded in a Bruker D8 ADVANCE X-ray powder diffractometer. Photoluminescence spectra and lifetimes of powder samples from 300 K down to 5 K were collected by a single-photon counting spectrometer using an Edinburgh FLS920 spectrometer with temperature-dependent equipped with a JANIS SHI-4S-1 cold head cooled by HC-4A compression engine. Using the software package provided by Edinburgh Instruments, all of the photoluminescent data were carefully analyzed. For example, lifetime data were fitted with triple-exponential-decay functions for 1 and 2, which are listed in Table S3-S19.


4

Page 5 of 25

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


Synthesis Synthesis of [Me2DABCO]2Cu4Br5(CN)3 (1): A mixture of CuCN (0.5 mmol, 0.045 g), KBr (1 mmol, 0.120 g), DABCO⋅6H2O (0.5mmol, 0.112 g) and MeOH (5 mL) was stirred and adjusted by CH3COOH to pH ca. 2, and then sealed in a 15-ml Teflon-lined stainless container and heated to 140 °C for 7 days. With a cooling rate of 5 °C min−1 to room temperature, generated colorless column crystals of 1 in 62% yield were recovered. Anal. Calc. for C19H36Br5Cu4N7 1: C, 22.46; H, 3.57; N, 9.65. Found: C, 22.59; H, 3.49; N, 9.51. IR(KBr, cm-1): 3422s, 2994m, 2356w, 2106s, 1636m, 1467m, 1151m, 1050m, 988w, 886w, 850m, 554w. Synthesis of [Me2DABCO]2Cu4I4.5(CN)3.5 (2): A mixture of CuCN (0.5 mmol, 0.045 g), KI (1 mmol, 0.167 g), DABCO⋅6H2O (0.5mmol, 0.112 g) and MeOH (5 mL) was stirred and adjusted by CH3COOH to pH ca. 2, and then sealed in a 15-ml Teflon-lined stainless container and heated to 140°C for 7 days. With a cooling rate of 5 °C min−1 to room temperature, generated colorless column crystals of 2 in 55% yield were recovered. Anal. Calc. for C19.5H36Cu4I4.5N7.5 1: C, 19.50; H, 3.02; N, 8.75. Found: C, 19.61; H, 2.96; N, 8.63. IR(KBr, cm-1): 3440s, 2993m, 2106s, 1634w, 1457m, 1366m, 1143m, 1041m, 888m, 849m, 544w. Caution: The synthetic procedure is potentially dangerous, because cuprous cyanide is dissolved in methanol solvent at acid condition, which might lead to generate highly toxic and dangerous hydrocyanic acid. To ensure safety, the amount of the experimental chemicals must not exceed the suitable scale described in synthetic method. Single Crystal X-ray Crystallography X-ray single-crystal diffraction data for 1 and 2 were collected at room temperature using the program SAINT and SADABS on a Agilent Technologies Gemini EOS diffractometer equipped with a Mo Kα (λ = 0.71073 Å) radiation. Direct method was used to solve the structure


5


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 6 of 25

using XS structure solution program, and the refinement was performed through full-matrix least-squares technique methods by using Olex2 version 1.2. All non-hydrogen atoms were refined anisotropically with anisotropic thermal parameters. All hydrogen atoms of organic cations were placed theoretically onto the specific carbon atoms, and refined with isotropic thermal parameters. The crystallographic data are listed in Table 1, selected bond lengths and bond angles are given in Table S1 and S2. Calculation Details TD-DFT calculations are carried out with ADF2016 program package.26,27 The PBE functional with TZP basis sets is used throughout. From statistical point of view, there are sixteen local geometries with full consideration of disordered occupancy of halide and cyanide, which are directly used as models for theoretical calculations. The singlet ground state and triplet excited state are calculated based on the sixteen local geometries. Indeed, many excited state orbitals involve Cu-Cu interactions, which is dependent on the structural geometries. To be noted, TD-DFT calculations do not include spin-orbit coupling, so that singlet-triplet excitation have zero oscillator strengths. RESULTS AND DISCUSSION Description of Structures X-ray single crystal diffraction analysis reveal that compound 1 features 3D halogeno(cyano)cuprate anionic open framework filled by Me2DABCO cations. It crystallizes in monoclinic space group C2/c, and the asymmetric unit consists of one crystallographically independent Cu(I) ion, 5/4 bromides, 3/4 cyanides, and half N,N′dimethyl-1,4-diazabicyclo-[2.2.2]octane (Me2DABCO) cation generated by in situ


6

Page 7 of 25

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


alkylation of DABCO (Figure 1a). The Cu(1) adopts a distorted tetrahedral geometry, occupied by Br(1), Br(1a), C(1)/N(1) and mixed Br(2)/N(2)/C(2) atoms. To be noted, Br(2) site is reasonably modeled as split, mixed Br–/CN– position and the corresponding occupancy ratio of Br–/CN– is 0.25/0.25. The Cu(1)-Br bond lengths are within the range 2.5341(6)–2.6066(7) Å and Cu(1)-N/C bond length are within the range 1.969(7)–1.972(3) Å. Correspondingly, Br-Cu(1)-Br angles are in the range of 99.72(2)–115.50(10)° and N/C-Cu(1)-Br angles are in the range of 105.6(4)–115.86(9)°. Two Cu(1) atoms are bridged by two µ2-Br(1) atoms into dinuclear unit with large Cu⋅⋅⋅Cu distance of 3.314 Å. The overall 3D halogeno(cyano)cuprate anionic open framework is built from [Cu4Br6(CN)] layered motifs and cyanides as linkers with channels filled by organic templates, assuming full occupancy of Br(2) sites. The [Cu4Br6(CN)] layers are constructed from 10-membered dumbbell-shaped [Cu10Br8(CN)2] rings with windows sized ca. 12.74 × 10.68 Å2 (Figure S2), which are linked by cyanides along the b-axis direction into anionic open framework. A calculation by platon reveals that 53.6% of the total volume is fully occupied by alkylated DABCO cations (Figure 1b). From topological point of view, the 3D anionic network can be described as a 65·8 CdSO4 topological net, in which Cu2Br2 cluster acts as a 4-connected node (Figure 1) and cyanides and Br(2) atoms act as linkers (Figure 2). When KI was instead of KBr under the same reaction conditions, isomorphic compound 2 was obtained, which also crystallizes in monoclinic space group C2/c, and the asymmetric unit consists of almost the same components except that iodides are instead of bromides. For 2, the I(2) sites are also partially occupied and the site occupancies are 0.125 (I–) and 0.375 (CN–), respectively. The Cu(1)-I bond lengths are


7


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 8 of 25

within the range 2.5215(7)–2.8065(9) Å and Cu(1)-N/C bond lengths are within 1.873(8)–1.940(4) Å. The I-Cu(1)-I angles and N/C-Cu(1)-I angles are in the range of 95.70(2)–116.90(6)° and 106.9(4)–114.93(14)°, respectively. Compared with 1, the distance of 3.703 Å between two adjacent Cu(1) atoms in 2 are larger. Similar to 1, the anionic framework of 2 is also 3D pillar-layered structure with dumbbell-shaped [Cu10I8(CN)2] windows sized ca. 13.51 × 10.91 Å2 (Figure S2), and there are onedimensional channels along b-axis direction accounting for about 52.5% of the total volume. To the best of our knowlegde, the 3D CdSO4-type frameworks with a short Schläfli symbol

(65·8)

are

first

observed

in

the

halocuprate,

cyanocuprate

and

halogeno(cyano)cuprate families, which are constructed by the Cu2X2 (X=Br, I) secondary building unit (SBU) linked by mixed halogenide and cyanide atoms. When the Cu2X2 SBUs are connected by pure halide atoms, only zero- or one-dimensional aggregates are found based on the survey of the reported halocuprate compounds, such as discrete binuclear [Cu2X6]4- cluster,28,29 tetranuclear [Cu4X10]2- cluster,30 1∞[Cu8X16]

2- 32

,

1∞[CuX2]

-

1∞[Cu2X4]

2- 31

,

anionic chain33 and so on. In addition, high-dimensional

halocuprate frameworks need to be supported by more complicated SBUs.34,35 If the Cu2X2 SBUs are connected by pure cyanide groups, the resulting halogeno(cyano)cuprate frameworks are not reported up to now. By Comparison with the number of crystalline halocuprate and cyanocuprate complexes, the halogeno(cyano)cuprate compounds are extremely few (only 10 compounds), in which coordination modes of halides and cyanides are not limited to µ2-bridge.36 It should be point out that all halide atoms and cyanide groups in 1 and 2 only serve as µ2-bridging modes to link copper(I) ions to form


8

Page 9 of 25

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


3D CdSO4-type halogeno(cyano)cuprate frameworks involving disorder of halogenide and cyanide. Photoluminescence Properties The photoluminescence of two isostructural compounds in the solid state was studied in detail. As shown in Figure S4, 1 and 2 display similar photoluminescence at room temperature in the solid state. 1 shows a strong emission band centered at 495 nm (τ = 72.5 µs) upon photoexitation at 295 nm. Similar to 1, compound 2 also exhibits a main emission peak centered at 478 nm (τ = 2.9 µs) upon excitation at 330 nm. The lifetime values for 1 and 2 are on the scale of microsceonds, which suggest the triplet state emission and phosphorescent character. Moreover, the quantum yields of 1 and 2 were measured to be 77.84% and 60.84%, respectively. The strong emission peaks at 495 nm for 1 and at 478 nm for 2 probably may be assigned as emission from a mixed chargetransfer (MLCT/XLCT) triplet excited state, which is a transition from the copper(I) and halide atoms to the unoccupied π* orbital of the cyanide ligand according to the literature.37 Strikingly, an interesting phenomenon is observed, that is, both 1 and 2 exhibit tunable photoluminescence upon varying wavelength of excitation light. As the excitation wavelength is changed from 310 nm to 350 nm, the strong emission band of 1 seems to be progressively red-shifted from 495 nm to 535 nm, accompanied by decreasing the emission intensity. With continuing to increase the excitation wavelength to 390 nm, the strong emission band has no obviously shift, but the emission intensity is generally reduced. To be noted, the lifetime of strong emission decreases intially and increases


9


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 10 of 25

subsequently (Table S9). In agreement with the variation of emission band, the fluorescent color change from blue (λex = 254 nm) to green (λex = 365 nm) reversibly, which can be distinguished by the naked eye or recorded by a digital camera (Figure 3). As expected, complex 2 also exhibits similar tunable emission by varying excitation wavelength from 320 nm to 390 nm. Along with increasing excitation wavelength from 320 nm to 360 nm, the intensity of main emission band in 2 is gradually decreased, accompanied by the redshift of main emission band (from 478 nm to 502 nm). Slightly different to 1, the redshift of emission peak is not very drastic and the color change of the emission is nearly indistinguishable by naked eyes (Figure 4). These phenomena seem to break Kasha’s rule, which states that the emission peaks are independent of the excitation wavelength because the excited electrons relax to the band edge before fluorescence begins without relation to their initial excitation energy. Such unusual phenomenon is similar to those observed in luminescent graphene quantum dots, which is often due to multicomponent graphene quantum dots.18 In order to deepen study on these tunable luminescent properties, solid-state emission spectra of 1 and 2 have been recorded by varying the excitation light from room temperature down to 5 K. Amazingly, the emission spectra of compound 1 exhibit a great difference at low temperature (Figure S5-S8). Especially when excited by 330 nm light, two main fluorescence peaks at ~570 nm and ~495 nm are commonly observed below 75 K, and their intensity is nearly comparable (Figure S6). While at room temperature only one main emission peak is observed, which seems to be red-shifted by increasing excitation wavelengths. In fact, when excited by 295-330 nm at room temperature, 1 displays the main emission at ~495 nm. With increasing excitation wavelength to 340 nm


10

Page 11 of 25

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


or more, the 495 peak nearly disappears. Different from 1, the emission spectra of 2 always show one main emission peak at any temperature, which seems to be red-shifted by variation of excitation light (Figure S9-S12). Although there are some differences in photochromic luminescent phenomena between 1 and 2, the color-change mechanism should be similar. Thus, 2 should also have two main emission bands centered at ~478 nm and ~502 nm, respectively. Two main emission bands for 1 and 2 indicating two independent excitation states can be attributed to the two independent clusters in these two solid solutions. It is worth mentioning that similar 3D halogeno(cyano)cuprate frameworks could show different emission bands related to different copper(I) clusters, in which the high ratio of CN to X tends to the red-shifted emission.36,37 Thus, two main emission for 1 and 2 may be caused by disordered occupancy of the X–/CN– sites. Due to complication, ambiguous knowledge and limited number of fully characterized luminescent mixed occupied halide-cyanide system, accurate predication on origin of chromisms is difficult at present. However, we carefully analyzed structure and performed theoretical calculations to help clarify the unusual emission. Take compound 1 for example, there are a large number of local geometries involving Cu2Br2 and mixed CN/Br from statistical point of view, and we numerated sixteen different geometries that were directly used as models to theoretical TD-DFT calculations. The results indicate that the highest occupied molecular orbitals (HOMOs) are mainly composed of copper(I) d orbitals mixing with a small amount of bromide p orbitals, while the lowest unoccupied molecular orbitals (LUMOs) are almost a contribution from metal-based orbitals, with admixture of π* orbitals of cyanide groups. The contributions of the luminescent emission bands can be mainly ascribed to a mixed chargetransfer triplet excited state, which is a transition from the copper(I) and halide atoms to the


11


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 12 of 25

unoccupied π* orbital of the cyanide mixing with a small quantity of metal-centered tranfer (d10 → d9S1 Cu). A maximum of the calculated excitation energy is about 3.71 eV (334 nm), which is comparable to the measured value of photoexcitation state (295 nm). From calculated results, there exists an excitation energy distribution associated with disorder of bromide and cyanide, which is possibly responsible for excitation-dependent emission (Figure 5). Remarkably, 1 exhibits interesting thermochromic luminescence upon being excited by 365 nm. Sample 1 was sealed in a sample tube, and then immersed into liquid nitrogen for a few minutes. When the sample was taken out from liquid nitrogen and exposed under a UV lamp (365 nm), the luminescence color progressively changes from yellowish-green to green. Solid-state emission spectra have been recorded with excitation at 365 nm from 300 K down to 5 K and corresponding data are reported in Table S10. At 300 K, the emission spectra (λex = 365 nm) display a single broad emission band centered at 535 nm for 1, with the decrease of temperature to 5 K, the emission band is progressively red-shifted to 570 nm. By lowing temperature, a bathochromic shift of 35 nm is truly reflected by a noticeable change in the color of the emission, accompanied by the emission intensity and lifetime increasing (Figure 6). This thermochromic luminescent property is often observed in copper(I)-halides with cubic Cu4I4 motifs, whose photoemission properties are mainly due to the variation of Cu⋅⋅⋅Cu interaction induced by change of temperature.38−42 Our calculated results also indicate that in spite of large Cu⋅⋅⋅Cu distance of 3.3 Å in 1, Cu-Cu bonding indeed exists in excitation orbitals and the charge transfer can occur between Cu-Cu nonbonding and Cu-Cu bonding. By lowering the temperature, the local environment of Cu is slight changed. As a result, the energy gap between the excitation state and the ground state has been narrowed, which lead to bathochromic shift of the emission


12

Page 13 of 25

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


accompanied by the lifetime increasing. While this thermochromic luminescent property is not found in compound 2. Conclusions In summary, two isostructural halogeno(cyano)cuprates have been successfully synthesized and characterized, which are 3D CdSO4-type framework involving disorder of halogenide and cyanide first observed in the halocuprate, cyanocuprate and halogeno(cyano)cuprate families. Both 1 and 2 exhibit finely tunable photoluminescent properties upon the variation of excitation light associated with disordered occupancy of bromide and cyanide. Surprisingly, in spite of large Cu⋅⋅⋅Cu distance of 3.3 Å in compound 1, it still

shows

unique

thermochromic

luminescence,

which

is

first

found

in

halogeno(cyano)cuprate materials. Such luminescent materials have potential application in light-sensing, thermal recording, color-changing LEDs and so on. ASSOCIATED CONTENT Supporting Information

Structural data at room temperature in CIF format, selected bond distances, packing arrays, synthesis route, PXRD patterns, UV-vis diffuse reflectance spectra, the solid-state luminescence spectra and emission lifetimes. This material is available free of charge via the Internet at http://pubs.acs.org AUTHOR INFORMATION Corresponding Author *Fax: +86 357 2051402. E-mail:[email protected]


13


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 14 of 25

ACKNOWLEDGMENT This work was ﬁnancially supported by 973 Program (2012CB821701), Ministry of Education of China (IRT1156), National Science Fund for Distinguished Young Scholars (20925101) and Sanjin Scholars. Table 1. Crystal data and structure refinement for complexes 1-2. Complex

1

2

Empirical formula

C19H36Br5Cu4N7

C19.5H36Cu4I4.5N7.5

Formula weight

1016.26

1200.77

Temperature

293(2) K

293(2) K

Crystal system

Monoclinic

Monoclinic

Space group

C2/c

C2/c

a (Å)

12.0799(7)

12.3116(9)

b (Å)

9.0881(4)

9.2665(4)

c (Å)

14.6088(11)

15.2149(10)

α (°)

90

90

β (°)

113.311

114.450(8)

γ (°)

90

90


14

Page 15 of 25

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


a

V (Å3)

1472.88(17)

1580.13(19)

Z

2

2

ρcalc, (g cm-3)

2.291

2.524

µ, (mm-1)

9.654

7.075

F(000)

980.0

1120.0

Size (mm)

0.42×0.11×0.07

0.36 × 0.08 × 0.06

θ(°)

2.897 to 32.059

2.843 to 29.2

Reflections/unique

3794 / 2314

6403 / 1893

Tmax /Tmin

0.551 / 0.107

1.000 / 0.467

Data / parameters

2314 / 0 / 88

1893 / 0 / 88

S

1.038

1.069

R1a, wR2b[I>2σ(I)]

0.0409, 0.0748

0.0329, 0.0607

R1a, wR2b(all data)

0.0622, 0.0819

0.0458, 0.0678

∆ρmax/∆ρmin(eǺ–3)

1.12/ -1.28

1.66 / -1.18

R1 = Fo-Fc/Fo, bwR2 = [w(Fo2-Fc2)2/w(Fo2)2]1/2


15


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 16 of 25

(a)

(b) Figure 1. View of dinuclear copper unit (a) and 3D organic templated open framework (b) in 1. Note: the site Br(2) has Br/CN occupancy of 0.25/0.25.

Figure 2. View of CdSO4 (a) net in 1.


16

Page 17 of 25

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 3. Photoluminescent emissions of 1 at various excitation wavelengths from 310 nm to 390 nm at room temperature. Insert: photoluminescent images of 1 excited at 254 nm and 365 nm.


17


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 18 of 25

Figure 4. Photoluminescent emissions of 2 at various excitation wavelengths from 320 nm to 390 nm at room temperature. Insert: photoluminescent images of 2 excited at 254 nm and 365 nm.

Figure 5. The highest occupied molecular orbitals (HOMOs) and the lowest unoccupied molecular orbitals (LUMOs) of 1 in different geometries.


18

Page 19 of 25

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 6. Temperature-dependent luminescence spectra excited at 365 nm from 5 K−300 K. Insert: photoluminescent images of 1 at 77 K and room temperature. REFERENCES 1. Deng, Z.; Tong, L.; Flores, M.; Lin, S.; Cheng, J.-X.; Yan, H.; Liu, Y. High-Quality Manganese-Doped Zinc Sulfide Quantum Rods with Tunable Dual-Color and Multiphoton Emissions. J. Am. Chem. Soc. 2011, 133, 5389-5396. 2. Nienhaus, K.; Nar, H.; Heilker, R.; Wiedenmann, J.; Nienhaus, G. U. Trans-Cis Isomerization is Responsible for the Red-Shifted Fluorescence in Variants of the Red Fluorescent Protein eqFP611. J. Am. Chem. Soc. 2008, 130, 12578-12579. 3. Cui, Y.; Yue, Y.; Qian, G.; Chen, B. Luminescent Functional MetalOrganic Frameworks. Chem. Rev. 2012, 112, 1126-1162. 4. Wen, T.; Zhang, D.-X.; Liu, J.; Zhang, H.-X.; Zhang, J. Facile synthesis of bimetal Au–Ag nanoparticles in a Cu(I) boron imidazolate framework with mechanochromic properties. Chem. Commun. 2015, 51, 1353-1355.


19


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 20 of 25

5. Balch, A. L. Dynamic Crystals: Visually Detected Mechanochemical Changes in the Luminescence of Gold and Other Transition-Metal Complexes. Angew. Chem. Int. Ed. 2009, 48, 2641-2644. 6. Shan, X.-C.; Zhang, H.-B.; Chen, L.; Wu, M.-Y.; Jiang, F.-L.; Hong, M.-C. MultistimuliResponsive Luminescent Material Reversible Switching Colors via Temperature and Mechanical Force. Cryst. Growth Des. 2013, 13, 1377-1381. 7. Sun, N.; Xiao, X.; Li, W.; Jiang, J. Multistimuli Sensitive Behavior of Novel Bodipy-Involved Pillar[5]arene-Based Fluorescent [2]Rotaxane and Its Supramolecular Gel. Adv. Sci. 2015, 2, 1500082(1-8). 8. Yoon, S.-J.; Chung, J. W.; Gierschner, J.; Kim, K. S.; Choi, M.-G.; Kim, D.; Park, S. Y. Multistimuli Two-Color Luminescence Switching via Different Slip-Stacking of Highly Fluorescent Molecular Sheets. J. Am. Chem. Soc. 2010, 132, 13675-13683. 9. Chen, Z.; Liang, J.; Nie, Y.; Xu, X.; Yu, G.-A.; Yin, J.; Liu, S. H. A novel carbazole-based gold(I) complex with interesting solid-state, multistimuli-responsive characteristics. Dalton Trans. 2015, 44, 17473-17477. 10. Han, M.; Cho, S. J.; Norikane, Y.; Shimizu, M.; Kimura, A.; Tamagawa, T.; Seki, T. Multistimuli-responsive azobenzene nanofibers with aggregation-induced emission enhancement characteristics. Chem. Commun. 2014, 50, 15815-15818. 11. Ni, W.-X.; Li, M.; Zheng, J.; Zhan, S.-Z.; Qiu, Y.-M.; Ng, S. W.; Li, D. Approaching WhiteLight Emission from a Phosphorescent Trinuclear Gold(I) Cluster by Modulating Its Aggregation Behavior. Angew. Chem. Int. Ed. 2013, 52, 13472-13476.


20

Page 21 of 25

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


12. Sun, D.; Wang, H.; Lu, H.-F.; Feng, S.-Y.; Zhang, Z.-W.; Sun, G.-X.; Sun, D.-F. Two birds with one stone: anion templated ball-shaped Ag56 and disc-like Ag20 clusters. Dalton Trans. 2013, 42, 6281-6284. 13. Li, B.; Huang, R.-W.; Qin, J.-H.; Zang, S.-Q.; Gao, G.-G.; Hou, H.-W.; Mak, T. C. W. Thermochromic Luminescent Nest-Like Silver Thiolate Cluster. Chem. Eur. J. 2014, 20, 1241612420. 14. Rachford, A. A.; Castellano, F. N. Thermochromic Absorption and Photoluminescence in [Pt(ppy)(µ-Ph2pz)]2. Inorg. Chem. 2009, 48, 10865-10867. 15. Wu, Z.-F.; Tan, B.; Wang, J.-Y.; Du, C.-F.; Deng, Z.-H.; Huang, X.-Y. Tunable photoluminescence and direct white-light emission in Mg-based coordination networks. Chem. Commun. 2015, 51, 157-160. 16. Wang, Z.-P.; Wang, J.-Y.; Li, J.-R.; Feng, M.-L.; Zou, G.-D.; Huang, X.-Y. [Bmim]2SbCl5: a main group metal-containing ionic liquid exhibiting tunable photoluminescence and white-light emission. Chem. Commun. 2015, 51, 3094-3097. 17. Lv, W.; Jiao, M.; Zhao, Q.; Shao, B.; Lü, W.; You, H., Ba1.3Ca0.7SiO4:Eu2+,Mn2+: A Promising Single-Phase, Color-Tunable Phosphor for Near-Ultraviolet White-Light-Emitting Diodes. Inorg. Chem. 2014, 53, 11007-11014. 18. Song, S. H.; Jang, M.-H.; Jeong, J.-M.; Yoon, H.; Cho, Y.-H.; Jeong, W.-I.; Kim, B.-H.; Jeon, S. Primary hepatocyte imaging by multiphoton luminescent graphene quantum dots. Chem. Commun. 2015, 51, 8041-8043. 19. Song, Y.; Fan, R.; Wang, P.; Wang, X.; Gao, S.; Du, X.; Yang, Y.; Luan, T. Copper(I)-iodide based coordination polymers: bifunctional properties related to thermochromism and PMMAdoped polymer film materials. J.Mater. Chem. C 2015, 3, 6249-6259.


21


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 22 of 25

20. Kitagawa, H.; Ozawa, Y.; Toriumi, K. Flexibility of cubane-like Cu4I4 framework: temperature dependence of molecular structure and luminescence thermochromism of [Cu4I4(PPh3)4] in two polymorphic crystalline states Chem. Commun. 2010, 46, 6302-6304. 21. Li, S.-L.; Zhang, F.-Q.; Zhang, X.-M. An organic-ligand-free thermochromic luminescent cuprous iodide trinuclear cluster: evidence for cluster centered emission and configuration distortion with temperature. Chem. Commun. 2015, 51, 8062-8065. 22. Benito, Q.; Goff, X. F. L.; Nocton, G.; Fargues, A.; Garcia, A.; Berhault, A.; Kahlal, S.; Saillard, J.-Y.; Martineau, C.; Trébosc, J.; Gacoin, T.; Boilot, J.-P.; Perruchas, S. Geometry Flexibility of Copper Iodide Clusters: Variability in Luminescence Thermochromism. Inorg. Chem. 2015, 54, 4483-4494. 23. Goforth, A. M.; Smith, M. D.; Peterson, L.; zur Loye, H.-C. Preparation and Characterization of Novel Inorganic-OrganicHybrid Materials Containing Rare, Mixed-Halide Anions of Bismuth(III). Inorg. Chem. 2004, 43, 7042-7049. 24. Saha, S.; Das, S.; Sen, D.; Ghorai, U. K.; Mazumder, N.; Gupta, B. K.; Chattopadhyay, K. K. Bane to boon: tailored defect induced bright red luminescence from cuprous iodide nanophosphors for on-demand rare-earth-free energy-saving lighting applications. J. Mater. Chem. C 2015, 3, 6786-6795. 25. Zhang, X.-M.; Hou, J.-J.; Guo, C.-H.; Li, C.-F. A New Class of Cuprous Bromide ClusterBased Hybrid Materials: Direct Observation of the Stepwise Replacement of Hydrogen Bonds by Coordination Bonds. Inorg. Chem. 2015, 54, 554-559. 26. Delley, B. An all-electron numerical method for solving the local density functional for polyatomic molecules. J. Chem. Phys. 1990, 92, 508-517.


22

Page 23 of 25

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


27. Delley, B. From molecules to solids with the DMol3 approach. J. Chem. Phys. 2000, 113, 7756-7764. 28. Kapoor, R.; Kataria, A.; Venugopalan, P.; Kapoor, P. New Tetranuclear Cu(II) Complexes: Synthesis, Structure, and Magnetic Properties. Inorg. Chem. 2004, 43, 6699-6706. 29. Valdés-Martínez, J.; Del Rio-Ramirez, M.; Hernández-Ortega, S.; Aakeröy, C. B.; Helfrich, B., Demonstrating the Importance of Hydrogen Bonds through the Absence of Hydrogen Bonds. Cryst. Growth Des. 2001, 1, 485-489. 30. Kelley, A.; Akkina, S.; Devarapally, G. K.; Nalla, S.; Pasam, D.; Madhabushi, S.; Bond, M. R., Nine compounds containing high-nuclearity [CunX2n+2]2− (n = 4, 5 or 7; X = Cl or Br) quasiplanar oligomers. Acta Crystallogra. C 2011, 67, m22-m34. 31. Margraf, G.; Bolte, M.; Wagner, M.; Lerner, H.-W., Synthesis and Crystal Structure of [Li(THF)4]Cu2Br4. J. Chem. Crystallogr. 2007, 37, 503-506. 32. Hou, J.-J.; Li, S.-L.; Li, C.-R.; Zhang, X.-M., In situ alkylation of N-heterocycles in organic templated cuprous halides. Dalton Trans. 2010, 39, 2701-2707. 33. Haddad, S. F.; AlDamen, M. A.; Willett, R. D.; Twamley, B., A copper(I) iodide chain with the 2-amino-4,6-dimethylpyridine cation. Acta Crystallogra. E 2004, 60, m76-m78. 34. Lei, X.-W.; Yue, C.-Y.; Zhao, J.-Q.; Han, Y.-F.; Yang, J.-T.; Meng, R.-R.; Gao, C.-S.; Ding, H.; Wang, C.-Y.; Chen, W.-D., Low-Dimensional Hybrid Cuprous Halides Directed by Transition Metal Complex: Syntheses, Crystal Structures, and Photocatalytic Properties. Cryst. Growth Des. 2015, 15, 5416–5426. 35. DeBord, J. R. D.; Lu, Y.-j.; Warren, C. J.; Haushalter, R. C.; Zubieta, J., Hydrothermal synthesis and structural characterization of [Cu(en)2]2Cu7Cl11: a three-dimensional openframework copper halide with occluded [Cu(en)2]2+ cations. Chem. Commun. 1997, 1365-1366.


23


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 24 of 25

36. Ding, R.; Zhai, Q.-G. Niu, J.-P.; Li, S.-N.; Jiang, Y.-C.; Hu, M.-C. Crystalline 3D openframework halogeno(cyano)cuprates synthesized in ionic liquids. CrystEngComm 2012, 14, 2626-2629. 37. Liu, X.; Guo, G.-C.; Wu, A. Q.; Cai, L.-Z.; Huang, J.-S. Two Halogeno(cyano)cuprates with Long-Lived and Strong Luminescence. Inorg. Chem. 2005, 44, 4282-4286. 38. Benito, Q.; Le Goff, X. F.; Maron, S.; Fargues, A.; Garcia, A.; Martineau, C.; Taulelle, F.; Kahlal, S.; Gacoin, T.; Boilot, J.-P.; Perruchas, S. Polymorphic Copper Iodide Clusters: Insights into the Mechanochromic Luminescence Properties. J. Am. Chem. Soc. 2014, 136, 11311-11320. 39. Kim, T. H.; Shin, Y. W.; Jung, J. H.; Kim, J. S.; Kim, J. Crystal-to-Crystal Transformation between Three CuI

Coordination Polymers and Structural Evidence for Luminescence

Thermochromism. Angew. Chem. Int. Ed. 2008, 47, 685-688. 40. Ford, P. C.; Cariati, E.; Bourassa, J. Photoluminescence Properties of Multinuclear Copper(I) Compounds. Chem. Rev. 1999, 99, 3625-3648. 41. Perruchas, S.; Tard, C.; Le Goff, X. F.; Fargues, A.; Garcia, A.; Kahlal, S.; Saillard, J.-Y.; Gacoin, T.; Boilot, J.-P. Thermochromic Luminescence of Copper Iodide Clusters: The Case of Phosphine Ligands. Inorg. Chem. 2011, 50, 10682-10692. 42. K. Yang, S.-L. Li, F.-Q. Zhang, X.-M. Zhang, Simultaneous Luminescent Thermochromism, Vapochromism, Solvatochromism, and Mechanochromism in a C3‑Symmetric Cubane [Cu4I4P4] Cluster without Cu−Cu Interaction. Inorg. Chem. 2016, 55, 7323-7325.


24

Page 25 of 25

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


For Table of Contents Use Only Light and Heat Dually Responded Luminescence in Organic Templated CdSO4-type Halogeno(cyano)cuprates with Disorder of Halogenide/Cyanide Shi-Li L, Jie Wang, Fu-Qiang Zhang, Xian-Ming Zhang

Two

isostructural

halogeno(cyano)cuprates

showing

excitation

wavelength

dependent

photoluminescence associated with disordered occupancy of halogenide and cyanide have been reported, and thermochromic luminescence is also observed, in spite Cu⋅⋅⋅Cu distances beyond sum of van der waals of two Cu(I) atoms.


25

Light and Heat Dually Responsive Luminescence in Organic

Recommend Documents