Synthesis of Structurally Diverse Emissive Molecular Rotors with Four

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Synthesis of Structurally-diverse Emissive Molecular Rotors with Four-component Ugi Stators Ma. Carmen García-González, Andres Aguilar-Granda, Angel Zamudio-Medina, Luis D. Miranda, and Braulio Rodríguez-Molina J. Org. Chem., Just Accepted Manuscript • DOI: 10.1021/acs.joc.7b02858 • Publication Date (Web): 19 Feb 2018 Downloaded from http://pubs.acs.org on February 20, 2018

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The Journal of Organic Chemistry

Synthesis of Structurally-diverse Emissive Molecular Rotors with Four-component Ugi Stators Ma. Carmen García-González,1 Andrés Aguilar-Granda,1 Angel Zamudio-Medina,2 Luis D. Miranda1* and Braulio Rodríguez-Molina1* 1

Instituto de Química, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad

Universitaria, Ciudad de México, 04510, México. 2

Departamento de Ciencias Básicas, Unidad Profesional Interdisciplinaria de Biotecnología del

Instituto Politécnico Nacional, Av. Acueducto s/n Barrio la Laguna Ticomán, Ciudad de México, 07340, México. Table of Contents

ACS Paragon Plus Environment

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Abstract The use of the multicomponent Ugi reaction to rapidly prepare a library of dumbbell-like molecular rotors is highlighted here. The synthetic strategy consisted on the atom-economic access to fifteen bulky and structurally-diverse iodinated stators, which were cross coupled to the 1,4-diethynylphenylene rotator. From those experiments, up to six rotors 1a-c and 1l-n were obtained, with yields ranging from 35 to 69 % per coupled C-C bond. In addition to the frameworks diversity, five of these compounds showed Aggregate-Enhanced Emission properties thanks to their conjugated 1,4-bis-[(phenyl)ethynyl]benzene cores, a property that rises by increasing the water fraction (fw) in their THF solutions. The results highlight the significance of the diversity-oriented synthesis of rapid access to new molecular fluorescent rotors. Introduction In the past years, there has been a great interest in the design and synthesis of artificial molecular machines (rotaxanes,1 catenanes,2 or motors3), which perform outstanding functions based on the ingenious combination of segmental motions. The inspiration for the envisioned properties in these compounds, whether in solution4 or in the solid state,5 has been drawn from biomolecular machines with synchronous motion in enzymes, or from macroscopic objects, like the collective movement of gears. The relevance of this area was undoubtedly emphasized when the Nobel prize in chemistry was awarded to J.-P. Sauvage, F. Stoddart, and B. Feringa in 2016.6 Within this field, the synthesis of compounds that show rotary motion, known as molecular motors7 or rotors,8 remains very attractive to numerous research groups. It is generally considered that controlling the motion in these compounds could enable the discovery of new


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technological applications.9 Several reports,10 have clearly pointed out that the rotation in these compounds could be favored when using a wheel-and-axis molecular architecture;11 that is, a relatively small group (termed rotator), linked to some voluminous groups with larger moment of inertia (termed stator). Usually, the construction of the rotors with this design can be carried out following a linear synthetic approach, based on several incremental steps and sometimes the final products require lengthy purification procedures. Although clearly successful, such linear methodology renders rotors with limited structural diversity, and may produce precursors or final products with low yields or very low solubility. Furthermore, these problems are often discovered in the final steps, forcing to re-design the synthetic routes.12 As the solubility and other properties of the molecules depend on the subtle differences in their molecular structures, a diversity-oriented approach may be an appropriate alternative that can help us to fine-tune some properties of the rotors, and avoid long synthetic procedures. In other words, it is highly desirable to find a synthetic alternative that allows a faster synthesis of molecular rotors, preferably with an increased variability of the frameworks. Along this line, it has been validated that multicomponent reactions (MCR) are a versatile tool to construct a vast range of molecular motifs in efficient and practical synthetic protocols. This approach has been useful to accelerate the discovery of new bioactive molecules, mainly in medicinal chemistry.13 One of the most appreciated features of this strategy is the feasibility to obtain large molecular complexity and diversity. Furthermore, the combination of a MCR with a post-condensation process gives access to diverse molecular libraries, offering the opportunity to vary the functional groups of the final products, normally in short synthetic sequences.


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Figure 1. Molecular rotors described in this work, based on a multicomponent stator synthesized from an Ugi reaction. Among the various MCRs,14 the four-component Ugi reaction stands out as a remarkable strategy due to its elegant simplicity.15 This approach is based on the reaction of four commercially available compounds, which produce bulky aminoacyl amide derivatives (adducts): an aldehyde, an amine, a carboxylic acid and an isocyanide. Furthermore, this reaction has other very appealing characteristics, for example: 1) the yields are typically high, 2) it can be carried out in one-pot at room temperature, 3) only one molecule of water is obtained as the sideproduct and 4) the purification of the adduct is generally straightforward. Therefore, we envisioned that the use of MCRs would enable the rapid synthesis of diverse molecular rotors with a wheel-and-axle molecular architecture. Considering the above, in this work we describe the synthesis, optimization and spectroscopic characterization of novel molecular rotors using Ugi adducts stators, which were coupled to 1,4diethynylphenylene fragment 4, which includes the rotator and the axis (Figure 1). These


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molecular components were selected to complement the Ugi stators for two main reasons: 1) the size of the 1,4-phenylene ring would be considerably smaller than the bulky aminoacyl amide derivatives, fulfilling the wheel-and-axle design and, 2) they would extend the conjugation of the resulting molecules, rendering compounds with emissive properties. To our knowledge, the use of this synthetic strategy has not been reported before and enabled the expedite synthesis of six diverse molecular rotors, showing yields from 35% to 69% per coupled carbon-carbon bond formed. Furthermore, five of these rotors showed aggregation-enhanced emission (AEE) in THFwater fraction mixtures, as determined by fluorescence experiments. The aggregation was corroborated by Dynamic Light Scattering (DLS) a glimpse of the conformational changes that occur during this process, was obtained by and 1H NMR experiments, carried out in THF/water mixtures. Results and Discussion Synthesis and characterization The synthesis of the envisioned Ugi rotors could be carried out following the routes illustrated in Scheme 1. In the pathway A, we considered that either a conjugated dibenzaldehyde or dianiline could take part of the Ugi reaction; whereas in the pathways B or C, a Sonogashira coupling would take place after the Ugi adducts were obtained. We explored the pathway A synthesizing either the dianiline 2a and dibenzaldehyde 2b, as described in detail in the Supporting information. With the dianiline 2a in our hands, we explored the Ugi reaction using acetic acid, benzaldehyde and cyclohexyl isocyanide as the additional components.


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Scheme 1. Retrosynthetic strategies to obtain Ugi Molecular rotors.

Unfortunately, the desired molecular rotor was not obtained under any of the explored conditions, and only a partial transformation was observed. Mass spectra and TLC chromatography indicated mainly the formation of two compounds, which were identified as one half of the expected Ugi-condensation (monocoupled fragment), and one decomposition product (imine). The reaction did not show any progress even if the mixture was kept stirring up to five days, so this pathway was not pursued further. Complementarily, we tried the Ugi reaction using the p-diethynylphenylenedibenzaldehyde 2b,16 but the very low solubility of this compound in methanol prevented any rotor formation (details provided in the Supporting Information). Next, we turned our attention to explore the alternative pathways B or C, which employ the Sonogashira coupling after synthesizing the Ugi adduct and differ only on the precursors (Scheme 1). It is important to mention that examples of this coupling reactions starting from Ugi adducts are relatively scarce, and they are limited to post-condensations, usually cyclizations.17 It was immediately noticed that one of the requirements for these routes to work was the inclusion of a halogen atom in Ugi structure, which could later be cross-coupled with an ethynyl moiety. To this end, commercial brominated and iodinated amines were used as starting materials. The


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Ugi adducts featuring bromide were obtained in moderate to good yields (see Supporting Information), but they presented exceedingly low reactivity towards the subsequent Sonogashira cross-coupling. After several attempts, we decided to use the iodide derivatives, which were also obtained in moderate to good yields (vide infra). Scheme 2. Synthesis of Ugi adduct 3a and its corresponding molecular rotor 1a.

To explore the synthesis of a molecular rotor following this approach, we used the adduct 3a as a test case, which was prepared in good yield (58 %), starting from 4-iodoaniline 7, benzaldehyde 8, benzoic acid 9 and cyclohexyl isocyanide 10 (Scheme 2). With the adduct 3a in hand, we carried out the double Sonogashira cross-coupling, using PdCl2(PPh3)2 as catalyst, CuI as cocatalyst, Et3N, and dry THF at room temperature, to give the desired rotor 1a in 15 % yield (Table 1, entry 1). After this promising result, we explored the effect of the temperature in this reaction. However, when the reaction was carried out at 50 ºC or higher, only traces of the desired compound were observed, and only a dehalogenated Ugi adduct was obtained (entries 2 and 3).


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Table 1. Survey of reaction conditions for molecular rotor 1a.

One well-known difficulty in this reaction is that the copper in the mixture could induce the free alkyne to react with itself, yielding the Glaser product (homocoupling).18 To explore the effect of the copper iodide, the Sonogashira cross coupling was carried out in the absence of this cocatalyst, but the desired product was not obtained (entry 4). Conversely, the use of a higher amount of CuI (10% mol), caused only a minor improvement of the yield (18 %, entry 5). When the reaction solvent was changed from THF to acetonitrile, the rotor 1a was obtained in a slightly better yield of 22 % (entry 6). Complementarily, the use of diisopropylethylamine (DIPEA) instead of triethylamine as a base, showed the best improvement in the yield (33 %), which corresponds to a 58 % yield per coupled C-C bond (entry 7). Since a small amount of starting material was still observed in this experiment, the reaction time was increased up to 108 h (entry 8), but the yield did not change significantly. Carrying out the reaction with different sources of Pd(0) or using other bases (entries 9-15), did not show any product. Finally, and


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inspired by the reported Sonogashira couplings under ball milling conditions,19 we explored the mechanochemical activation of the reaction using a planetary mill, obtaining very low yields (see the Supporting Information).

HN

HN

O

O O

HN

O

N

Cy

HN

O

N

O

N

O

I

I O 2N

HN O

O

N

O

I H3CO

N

I H3CO

I F

Cl

HN

3d, 83 %

3c, 98 %

3b, 89 % Cy

3f, 86 %

3e, 79 %

HN

O

HN HN

O O

O O

N

O O

N O

O

N

NH I

F O

N

N

I

I

I CH3

CH3

I

3h, 55 %

3g, 74 % O

HN

NH

HN O

O

N

I

O

3j, 72 %

3i, 93 %

O

N

O Ph

HN

I

Cy O

N

O Ph

3k, 68%

I

N Ph

I

3l, 97 %

3m, 71 %

3n, 82 %

3o, 47 %

Figure 2. Iodinated Ugi adducts that were synthesized and examined as voluminous stators. After we found the best reaction conditions for the synthesis of rotor 1a, we explored the scope of this protocol. We first focused on the synthesis of the several Ugi adducts 3, carrying out the reaction at room temperature in methanol in 24 h with moderate to good yields (47-80 %). In this way, we prepared fifteen (3a-o) Ugi adducts. Eleven of them (3a-i and 3k-l) using benzaldehyde, tert-butyl isocyanide or cyclohexyl isocyanide, the corresponding carboxylic acid and a halogenated amine (Figure 2). Another four Ugi adducts (3j and 3m-o), were prepared using the iodide atom appended to the carboxylic acid (Figure 2). All synthesized compounds were fully characterized by spectroscopic methods (NMR and IR), as well as high-resolution mass


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spectrometry. Having the Ugi adducts in our hands, we focused on the synthesis of the rotors by a double Sonogashira reaction. Although all the Ugi adducts were cross-coupled with the 1,4diethynylphenylene compound 4, some of the resulting rotors showed low yields or persistent impurities difficult to remove by column chromatography. These side-products were in some cases traces of starting materials or traces of de-halogenated adducts, and those rotors are not reported in detail here.

O

O

O NH

N

N

O

O NH

HN

HN

N

N

O

O

Cl

O

Cl

O2N

NO2 1c, 47 %

1b, 12 %

O O

O O

HN

NH N

N

1l, 47 %

O

O

N

N

O

O

O NH

HN

O

HN N

H N

N O

1m, 27 %

O

1n, 28 %

Figure 3. Molecular rotors with four-component Ugi stators reported here. Among the successful attempts, the molecular rotor 1b was obtained in a modest yield of 12 % (35 % per coupled carbon-carbon bond formed), starting from the Ugi adduct 3b. Comparatively, an electron-withdrawing group in the carboxylic precursor 3c, afforded the molecular rotor 1c with a much better yield of 47 % (68 % per coupled carbon-carbon bond formed). Subsequently, we found that the position of the halogen in the Ugi precursor is of great importance, because when the adduct 3k was used, which was obtained from 2-iodoaniline, only degradation products


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were observed. Conversely, when the compound 3l was employed, which was obtained from 3iodoaniline, the desired rotor 1l was obtained in a good 47 % yield (69 % per coupled carboncarbon bond formed). Complementarily, the adduct 3m was used to obtain the molecular rotor 1m in 27 % yield (52 % per coupled carbon-carbon bond formed), and the compound 3n, allowed us to obtain the compound 1n in a moderated yield of 28 % (53 % per coupled carboncarbon bond formed), as shown in Figure 3. Fluorescence and structural studies Single-channel recording of fluorescence intensity has become a valuable tool for molecular rotors, since fluorescence emission techniques are highly dependent and sensitive to dynamic rotations and conformational changes on the excited state.20 Once the six molecular rotors 1a-c and 1l-n were successfully characterized, we focused on their fluorescence properties resulting from the conjugated 1,4-bis-[(phenyl)ethynyl]benzene core, a moiety that has been commonly employed in highly emissive molecules.21 The studies were performed in THF solutions of 1 x 10-6 M concentration at room temperature, due to the high solubility of the rotors in this solvent (Figure 4a). Gratifyingly, three out of six rotors presented strong emissive properties, for example the excitation at λexc = 340 nm afforded a well vibrationally-resolved pattern with a peak of maximum intensity at λem = 350 nm for compound 1n (фf = 0.5). Using the same excitation wavelength, a peak was observed at λem = 410 nm for compound 1a (фf = 0.12). Using λexc = 325 nm, an emission at λem = 354 nm was observed for compound 1l (фf = 0.27). Conversely, the emission of compounds 1m (λexc = 340 nm, λem =390 nm, фf = 0.05) and 1b (λexc = 335 nm, λem = 400 nm, фf = 0.04) was low. Unsurprisingly, the rotor 1c with deactivating (quenching) -NO2 groups was barely fluorescent (λexc = 340 nm, λem = 400 nm, фf = 0.007). The relevant optical properties have been compiled in Table 2.


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Table 2. Optical properties of compounds 1a-c and 1l-n (in alphabetical order). Compound

λmax abs (nm)

λem PL (nm) 410

Stokes shift -1 (cm ) 1.42E+05

1a

340

1b

фf 0.12

335

400

1.53E+05

0.04

1c

340

400

1.66E+05

0.007

1l

325

354

3.44E+05

0.27

1m

340

390

2.08E+05

0.05

1n

340

350

1.00E+07

0.50

Despite the good observed emission of the three rotors 1n, 1a and 1l, we pondered that the conformational changes and the intramolecular motion in these conjugated molecules could deactivate the excited states, thus reducing the emission intensity. If this hypothesis was correct, then any process in which the internal motion is reduced would increase the observed emission, as reported in numerous compounds with Aggregation-Induced Emission (AIE) effect.22 With the aim to explore the role of the particle formation in the emission properties, an AIE protocol was conducted for all the rotors.23 Due to the insolubility of the rotors in water, a higher water fraction in their THF solution might force the formation of aggregates, possibly increasing the initial fluorescence. Therefore, all the fluorescence experiments were carried out using different THF/water fraction mixtures (fw) as described in the experimental section.


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Figure 4. a) Comparison of the fluorescence emission spectra of the molecular rotors reported here (1x10-6 M in THF). Emission of rotors with different THF/water fractions and the corresponding excitation wavelengths: b) Compound 1n (λexc= 340 nm), c) Compound 1a (λexc= 340 nm), d) Compound 1l (λexc= 325 nm). The water fraction experiments of compound 1n exhibited a slight increment in its relative emission intensity, as shown in Figure 4b, up to a THF/water fraction of 50%. Then, when the water fraction becomes higher than 50%, the emission decreases abruptly. This fluorescence quenching was attributed to the light-scattering caused by the formation of larger aggregates, or to the fact that some aggregates precipitate and/or they adhere to the walls of the cuvette. Gratifyingly, a more noticeable change was observed in compounds 1a and 1l (Figure 4c and 4d). These two rotors showed a significant emission enhancement when using water fractions


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from fw = 0 to 50% (1a) or from fw = 0 to 70% (1l), respectively. Again, higher water fractions caused fluorescence quenching, which was attributed to the above-mentioned reasons. Considering that the low emissive rotors (1b, 1c and 1m) could also show analogous emissionenhancement properties, we carried out the corresponding THF/water fraction experiments (see Supporting Information). Interestingly, rotor 1b showed very small emission enhancement in water fractions from fw = 0% to 60%, but a significant increase was observed with water fractions between fw = 70% and 90%, indicating that emissive aggregates are favored under high fw conditions. On the other hand, the rotor 1c which bears -NO2 groups in the stator, did not show any emission improvement, but only a complete quenching under those conditions. Finally, a slight enhancement was observed in rotor 1m only up to fw = 30%, but higher water fractions quenched the fluorescence. The significant enhanced-emission observed in the rotors 1a, 1l, and 1n (also in 1m to some extent), can be attributed to the aggregate formation.24 We further investigated the aggregation of the rotor 1l, by means of dynamic light scattering (DLS), a technique that is commonly used to determine the size distribution of small particles in suspensions.25 For a better comparison, the DLS studies were carried out under the same concentration conditions of the PL experiments. The DLS analyses confirmed that when the rotor is completely dissolved in THF, there are no particles in the solution (see Supporting Information). Subsequently, the addition of water gave rise to a bimodal distribution of particles, that is, the coexistence of minute particles of 3.21 nm and larger aggregates of 345 nm at fw = 20 %. Larger particles with size of ca. 540 nm, were later obtained at higher water fractions (fw = 30%). Finally, at fw = 60 % the distribution of particles became monomodal, showing very large particles of 1774 nm in size (see Supporting Information).


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Once we confirmed the particle formation, we carried out 1H NMR experiments of the rotor 1l to gain more information about the structural changes that may occur during aggregation.26 The experiments were carried out starting from a pure THF solution and subsequently, D2O was gradually added in fw = 10% steps. Indeed, given the fact that the compound is not soluble in water, at fractions above fw = 50% the particles were so large that they started to precipitate, and thus the NMR signal was lost. Nevertheless, we were able to obtain the spectra using water fractions between 10% and 50%, as shown in Figure 5.

Figure 5. 1H NMR of compound 1l in different THF-d8/D2O fractions at 300 MHz. The red asterisk indicates the signal corresponding to the central phenylene ring and the blue dot shows the displacement of the -NH hydrogen. The inserts highlight the changes in the chemical shifts of the protons in the phenylene and the amide group.


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As evidenced by the 1H NMR spectra of 1l, all the signals showed large fluctuations of their chemical shifts immediately after the first addition of water (fw = 10 %), as compared with the spectrum obtained in pure THF-d8. By using 2D NMR sequences (DEPT135, HETCOR and FLOCK), it was possible to assign the signals corresponding to the central benzene ring as a singlet at 7.42 ppm and the one from the N-H group at 7.05 ppm. The inserts in Figure 5 highlight the abrupt changes of these signals, which are easily distinguishable compared to other severely overlapped signals in the aromatic region. It seems possible to say that the interaction between neighboring Ugi stators is favored during aggregation, which could reduce the internal motion of the whole molecule, thus increasing the emission. Complementary variable-temperature 1H NMR experiments of rotor 1l in pure THF-d8 helped us to gain a deeper insight of the structural changes during the aggregation process caused by water. To better describe the structural changes, we used the signal coming from the central benzene ring as the main probe. The central protons are magnetically equivalent due to a chemical exchange that is faster than the timescale of the technique (at room temperature). If the frequency of this motional process is reduced at lower temperature, the signal would gradually become broader and smaller, until the chemical exchange becomes very slow, and the initial peak would split into two signals, as described in a de-coalescence process.27 In our experiments, this peak progressively shifted and became broader until it practically disappeared at 233 K, in complete agreement with the expected line shape change of a reduced rotational process, improving the planarization of the 1,4-bis-[(phenyl)ethynyl]benzene core, thus increasing the emission (Figure 6). Very low temperatures would finally cause the anticipated splitting of the signal, which could allow us to extract a precise activation barrier to rotation of this molecular fragment; however, these experiments could not be carried out due to


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the low solubility of the rotor 1l at that temperature and due to limitations of our spectrometer. Similarly, the signal from the N-H group also shifted gradually (insert in Figure 6), suggesting that the low temperature experiments also have an impact on the molecular conformation of the Ugi stators.

Figure 6. VT 1H NMR of 1l in pure THF-d8 at 300 MHz. The red asterisk indicates the signal corresponding to the central phenyl ring and the blue dot shows the displacement of the -NH hydrogen. The inserts highlight the changes in the chemical shifts of the protons in the phenylene and the amide group. It should be emphasized that although only these two signals (central benzene ring and N-H) are described here in a detailed fashion, all the signals from the spectrum showed changes in their chemical shifts, indicating that the low temperature reduces the internal motion also in the Ugi stators. As described in the literature,28 this restriction also gives rise to an improvement of the


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emission properties. We corroborated the significant emission enhancement at low-temperature by carrying out fluorescence experiments of the rotor 1l in pure THF from 293 K to 253 K (see Supporting Information). Considering all the 1H NMR and fluorescence experiments together, is evident that the structural changes in THF-water mixtures are different than those observed at low temperature in pure THF. To assess the role of the water in this process, not only the aggregation but also the fluorescence studies could be carried out using a polar aprotic solvent miscible with THF, for example DMF or acetone; unfortunately, the synthesized rotors were completely or partially soluble in those solvents, preventing further experiments. Conclusions We describe here for the first time a diversity-oriented synthesis to obtain six structurally-diverse rotors with moderate to good yields (35-69 % per coupled C-C bond formed). We started with the synthesis of fifteen iodinated bulky stators that were then coupled to the 1,4-bis[(phenyl)ethynyl]benzene core. Most of the resulting rotors showed moderate to good fluorescence in THF solution, except the one bearing the deactivating -NO2 group, which was not emissive. Subsequently, we conducted an aggregated-induced emission (AIE) protocol to increase the fluorescence of these rotors. Remarkably, stronger emissions were documented when using progressively higher water fractions in their THF solutions, causing the rotors to form aggregates, confirmed by DLS experiments. From these studies, it can be concluded that the presence of water forces the existence of highly emissive aggregates, favoring conformational


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changes of the whole molecule, as evidenced by 1H NMR experiments carried out in THFd8/D2O. In summary, we have demonstrated that the use of multicomponent reactions is an excellent alternative to obtain diversity-oriented molecular rotors. This strategy significantly shortens the typical linear synthetic sequences, and affords structures that could be subsequently modified, if desired. Our results highlight the significance of the synthesis of diversity-oriented molecular rotors with enhanced emissive properties resulting from aggregation. Subsequent structural modifications and the use of other MCRs to construct new molecular rotors are currently underway. Experimental Section Material and methods All reagents were purchased from Sigma-Aldrich and used as received. Flash column chromatography was performed using Aldrich silica gel 230-400 mesh, hexane and ethyl acetate as eluents. Reactions were monitored by TLC on silica gel plates 60 F254 (Merck) and the spots were detected either by UV-absorption or by using Seebach’s TLC stain followed by heating. 1H and

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C NMR spectra were recorded at ambient temperature using Bruker Fourier 300, Jeol

Eclipse 300 spectrometers, chemical shifts (δ) are reported in ppm relative to the solvent signal, with an internal TMS standard, NMR coupling constants are reported in hertz (Hz). The FT-IR spectral data were recorded with Bruker ATR in the 450-4000 cm-1 range. High-resolution mass spectra were recorded on a JEOL AccuTOF JMS-T100LC mass spectrometer with TOF mass analyzer. FAB+ mass spectra were obtained on a 3-nitrobenzyl alcohol matrix in the positive ion mode on the MStation JMS-700 spectrometer, operated at an accelerating voltage of 10 kV by


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using Xenon atoms at 6 keV. Melting points were determined using Fisher Johns melting point apparatus (uncorrected). The absorption spectra were acquired in a Cary 50 spectrometer, and fluorescence spectra were acquired in a Cary Eclipse fluorimeter (Varian). The quantum yields (фf) were determined in cyclohexane using Coumarin 102 as the reference. DLS experiments were performed in a Malvern Instruments Ltd equipment with a laser NIBS (Non-Invasive Back Scattering) at 298 K, using a THF solution of 1l at 1x10-6 M and Milli-Q water. The solution was filtered through an inorganic Anatop membrane (Whatman) with a 0.02 µ pore size. Immediately after preparing the mixtures (THF/water), the cuvette was introduced into the DLS equipment provided with a laser diode (wavelength = 633 nm). The analyses of the hydrodynamic radius (RH) were performed with the Zetasizer software version 7.12. General procedure for the Ugi adducts The Ugi 4-CR were carried out by mixing in one round bottom flask, the corresponding benzaldehyde (1.0 equiv), the appropriate amine (1.0 equiv), the benzoic acid derivative (1.0 equiv) and the isocyanide (1.0 equiv) in MeOH. The reaction mixture was stirred at room temperature for 24 hours. The solvent was removed under reduced pressure. The crude product was purified by flash chromatography on silica using hexanes:EtOAc as eluent, to afford the corresponding Ugi adduct. General procedure for Sonogashira coupling In a round bottom flask were dissolved the Ugi adduct (2.0 equiv), 1,4-diethynylbenzene (1.0 equiv), PdCl2(PPh3)2 (10 % mol) and CuI (5 % mol) in degassed acetonitrile. To this suspension was added degassed N,N-diisopropylethylamine and the mixture was stirred to room temperature under nitrogen atmosphere from 24 to 48 hours. After this reaction time, am aqueous solution of


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saturated NH4Cl was added to the mixture and the organic layers were extracted with dichloromethane (3 × 20 mL). The organic layers were dried over Na2SO4 and evaporated under reduced pressure. The residue was purified by flash column on silica with hexanes:EtOAc as eluents to afford the corresponding molecular rotor. N-(2-(cyclohexylamino)-2-oxo-1-phenylethyl)-N-(4-iodophenyl)benzamide (3a) The compound 3a was synthesized using the following quantities: 4-iodoaniline (0.60 g, 2.7 mmol), benzaldehyde (0.29 g, 2.7 mmol), benzoic acid (0.34 g, 2.7 mmol) and cyclohexyl isocyanide (0.3 g, 2.7 mmol) and purified by flash column chromatography (eluent 80:20 hexane/EtOAc). The product was obtained as a white solid (0.85 g, 58 %, m.p. 220-222 °C). IRνmax: 3273, 2930, 2851, 1675, 1628, 1558, 1377 cm-1. 1H NMR (300 MHz, CDCl3) δ: 7.337.16 (m, 13H), 6.74 (d, 2H, J= 8.1 Hz), 6.22 (s, 1H), 5.67 (d, 1H, J= 8.0 Hz), 4.94-3.81 (m, 1H), 2.00-1.92 (m, 2H), 1.73-1.56 (m, 3H), 1.43-1.30 (m, 2H), 1.20-1.01 (m, 3H).

13

C NMR (75

MHz, CDCl3) δ: 171.2, 168.5, 141.0, 137.5, 135.8, 134.7, 132.4, 130.3, 129.7, 128.7, 128.5, 127.9, 92.6, 66.0, 48.9, 32.9, 25.6, 24.8. HRMS (EI+) calculated for C27H27IN2O2

[M]+

538.1117; found 538.1135. N-(2-tert-butylamino)-2-oxo-1-phenylethyl)-N-(4-iodophenyl)benzamide (3b) The compound 3b was synthesized using the following quantities: 4-iodoaniline (0.79 g, 3.6 mmol), benzaldehyde (0.40 g, 3.6 mmol), benzoic acid (0.44 g, 3.6 mmol) and tert-butyl isocyanide (0.30 g, 3.6 mmol) and purified by flash column chromatography (eluent 80:20 hexane/EtOAc). The product was obtained as a white solid (1.64 g, 89 %, m.p. 193-195 °C). IRνmax: 3426, 3279, 2966, 1675, 1627, 1384, 1358 cm-1. 1H NMR (300 MHz, CDCl3) δ: 7.317.27 (m, 4H), 7.24 (s, 5H), 7.20-7.14 (m, 3H), 6.75 (d, 2H, J= 9.0 Hz), 6.14 (s, 1H), 5.69 (s, 1H),


21


1.36 (s, 9H).

13

Page 22 of 35

C NMR (75 MHz, CDCl3) δ: 170.9, 168.5, 140.9, 137.3, 135.7, 134.7, 132.2,

130.1, 129.6, 128.6, 128.5, 128.5, 127.7, 92.4, 66.4, 51.7, 28.6. HRMS (EI+) calculated for C25H25IN2O2 [M]+ 512.0961; found 512.0960. N-(2-tert-butylamino)-2-oxo-1-phenylethyl)-4-chloro-N-(4-iodophenyl)-3-nitrobenzamide (3c) The compound 3c was synthesized using the following amounts: 4-iodoaniline (0.62 g, 2.8 mmol), benzaldehyde (0.3 g, 2.8 mmol), 4-chloro-3-nitrobenzoic acid (0.57 g, 2.8 mmol) and tert-butyl isocyanide (0.23 g, 2.8 mmol) and purified by flash column chromatography (eluent 80:20 hexane/EtOAc). The product was obtained as a white solid (1.65 g, 98 %, m.p. 151-153 °C). IRνmax: 3306, 3232, 1683, 1633, 1540, 1359 cm-1. 1H NMR (300 MHz, CDCl3) δ: 7.82 (d, 2H, J= 2.1 Hz), 7.33-7.29 (m, 3H), 7.24-7.15 (m, 4H), 7.11-7.09 (m, 2H), 6.69 (s, 2H), 6.04 (s, 1H), 5.39 (s, 1H), 1.29 (s, 9H). 13C NMR (75 MHz, CDCl3) δ: 167.9, 167.2, 147.2, 139.6, 137.9, 135.6, 133.9, 132.8, 132.3, 131.4, 130.3, 129.0, 128.8, 128.4, 126.0, 93.6, 66.5, 52.0, 28.6. HRMS (DART+) calculated for C25H24ClIN3O4 [M+H]+ 592.0500; found 592.0506. N-(2-(cyclohexylamino)-2-oxo-1phenylethyl)-N-(4-iodophenyl)-3-methoxybenzamide (3d) The compound 3d was synthesized using the following amounts: 4-iodoaniline (0.60 g, 2.7 mmol), benzaldehyde (0.29 g, 2.7 mmol), 3-methoxybenzoic acid (0.41 g, 2.7 mmol) and cyclohexyl isocyanide (0.30 g, 2.7 mmol) and purified by flash column chromatography (eluent 80:20 hexane/EtOAc). The product was obtained as a white solid (1.29 g, 83 %, m.p. 161–163 °C). IRνmax: 3264, 3065, 2928, 1646, 1590, 1556, 1336 cm-1. 1H NMR (300 MHz, CDCl3) δ: 7.34-7.19 (m, 8H), 7.09-6.97 (m, 1H), 6.87-6.80 (m, 2H), 6.77-6.71 (m, 2H), 6.19 (s, 1H), 5.68 (d, 2H, J= 8.2 Hz), 3.90-3.80 (m, 1H), 3.64 (s, 3H), 2.03-1.81 (m, 2H), 1.61 (m, 3H), 1.41-1.25


22

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(m, 2H), 1.19-1.00 (m, 3H).

13

C NMR (75 MHz, CDCl3) δ: 170.9, 168.5, 159.0, 141.0, 137.5,

137.0, 134.5, 132.4, 130.3, 129.0, 128.7, 121.0, 116.3, 113.4, 92.7, 66.1, 55.3, 48.9, 32.9, 25.5, 24.8. HRMS (EI+) calculated for C28H29IN2O3 [M]+ 568.1223; found 568.1213. N-(2-(tert-butylamino)-2-oxo-1-phenylethyl)-N-(4-iodophenyl)-3-methoxybenzamide (3e) The compound 3e was synthesized using the following amounts: 4-iodoaniline (0.79 g, 3.6 mmol), benzaldehyde (0.38 g, 3.6 mmol), 3-methoxybenzoic acid (0.55 g, 3.6 mmol) and tertbutyl isocyanide (0.30 g, 3.6 mmol) and purified by flash column chromatography (eluent 80:20 hexane/EtOAc). The product was obtained as a white solid (1.54 g, 79 %, m.p. 107–109 °C). IRνmax: 3284, 3078, 2963, 1680, 1628, 1559, 1382 cm-1. 1H NMR (300 MHz, CDCl3) δ: 7.337.20 (m, 8H), 7.06-7.01 (m, 1H), 6.86-6.82 (m, 2H), 6.77-6.72 (m, 2H), 6.10 (s, 1H), 5.65 (s, 1H), 3.64 (s, 3H), 1.35 (s, 9H). 13C NMR (75 MHz, CDCl3) δ: 170.8, 168.6, 159.0, 137.5, 137.0, 134.8, 132.3, 130.2, 129.0, 121.1, 116.3, 113.5, 92.6, 66.6, 55.3, 51.8, 28.7. HRMS (EI+) calculated for C26H27IN2O3 [M]+ 542.1066; found 542.1092. N-(2-(tert-butylamino)-2-oxo-1-phenylethyl)-3-fluoro-N-(4-iodophenyl)benzamide (3f) The compound 3f was synthesized using the following amounts: 4-iodoaniline (0.72 g, 3.2 mmol), benzaldehyde (0.34 g, 3.2 mmol), 3-fluorobenzoic acid (0.45 g, 3.2 mmol) and tert-butyl isocyanide (0.27 g, 3.2 mmol) and purified by flash column chromatography (eluent 80:20 hexane/EtOAc). The product was obtained as a white solid (1.46 g, 86 %, m.p. 205–207 °C). IRνmax: 3281, 3072, 1679, 1630, 1555, 1439, 1358, 1225 cm-1. 1H NMR (300 MHz, CDCl3) δ: 7.35-7.18 (m, 7H), 7.15-7.01 (m, 3H), 6.96-6.87 (m, 1H), 6.76 (d, 2H, J= 7.9 Hz), 6.14 (s, 1H), 5.65 (s, 1H), 1.36 (s, 9H).

13

C NMR (75 MHz, CDCl3) δ: 169.9, 168.3, 163.6, 160.3, 140.3,

137.9, 137.5, 134.4, 132.3, 130.2, 129.5, 129.4, 128.7, 124.2, 116.8, 11.6, 115.8, 115.5, 92.9,


23


Page 24 of 35

66.4, 51.8, 28.7. HRMS (DART+) calculated for C25H25FIN2O2 [M+H]+ 531.0944; found 531.0967. N-(2-(cyclohexylamino)-2-oxo-1-phenylethyl)-N-(4-iodophenyl)-4-methylbenzamide (3g) The compound 3g was synthesized using the following amounts: 4-iodoaniline (0.79 g, 3.6 mmol), benzaldehyde (0.38 g, 3.6 mmol), 3-methylbenzoic acid (0.49 g, 3.6 mmol) and cyclohexyl isocyanide (0.39 g, 3.6 mmol) and purified by flash column chromatography (eluent 80:20 hexane/EtOAc), the product was obtained as a white solid (1.45 g, 74 %, m.p. 212-214 °C). IRνmax: 3438, 3277, 2929, 1662, 1626, 1552, 1385 cm-1.

1

H NMR (300 MHz, CDCl3) δ:

7.35-7.19 (m, 10H), 6.97 (d, 2H, J= 8.11 Hz), 6.74g (d, 2H, J= 8.11 Hz), 6.20 (s, 1H), 5.69 (d, 1H, J= 8.3 Hz), 3.92-3.81 (m, 1H), 2.26 (s, 3H), 1.99-1.90 (m, 2H), 1.68-1.59 (m, 3H), 1.42-1.27 (m, 3H), 1.20-1.04 (m, 3H).

13

C NMR (75 MHz, CDCl3) δ: 171.2, 168.6, 141.4, 140.0, 137.5,

134.8, 133.4, 132.8, 130.2, 128.8, 128.7, 128.6, 92.5, 66.2, 48.9, 32.9, 25.6, 24.8, 21.3. HRMS (EI+) calculated for C28H29IN2O2 [M]+ 552.1274; found 552.1282. N-(2-tert-butylamino)-2-oxo-1-phenylethyl)-N-(4-iodophenyl)-4-methylbenzamide (3h) The compound 3h was synthesized using the following amounts: 4-iodoaniline (0.79 g, 3.6 mmmol), benzaldehyde (0.38 g, 3.6 mmol), 3-methylbenzoic acid (0.49 g, 3.6 mmol) and tertbutyl isocyanide (0.30 g, 3.6 mmol) and purified by flash column chromatography (eluent 80:20 hexane/EtOAc). The product was obtained as a white solid (1.04 g, 55 %, m.p. 142-144 °C). IRνmax 3295, 3065, 2922, 1672, 1625, 1484, 1384, 1361 cm-1. 1H NMR (300 MHz, CDCl3) δ: 7.33-7.19 (m, 10H), 6.95 (d, 2H, J= 8.0 Hz), 6.74 (d, 2H, J= 8.0 Hz), 6.14 (s, 1H), 5.76 (s, 1H), 2.24 (s, 3H), 1.35 (s, 9H).

13

C NMR (75 MHz, CDCl3) δ: 171.0, 168.6, 144.2, 141.3, 139.9,


24

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137.9, 134.8, 132.7, 132.2, 130.0, 129.1, 128.7, 128.5, 128.4, 117.3, 92.4, 6.6, 51.7, 28.7, 21.4. HRMS (DART+) calculated for C26H28IN2O2 [M]+ 527.1195; found 527.1183. N-(2-((2,6-dimethylphenyl)amino)-2-oxo-1-phenylethyl)-N-(4-iodophenyl)benzamide (3i) The compound 3i was synthesized using the following amounts: 4-iodoaniline (0.72 g, 3.2 mmol), benzaldehyde (0.34 g, 3.2 mmol), benzoic acid (0.40 g, 3.2 mmol) and 2,6dimethylphenyl isocyanide (0.43 g, 3.2 mmol) and purified by flash column chromatography (eluent 80:20 hexane/EtOAc). The product was obtained as a white solid (1.67 g, 93 %, m.p. 90– 93 °C). IRνmax: 3264, 3030, 1645, 1526, 1481, 1340 cm-1. 1H NMR (300 MHz, CDCl3) δ: 7.397.35 (m, 2H), 7.33-7.27 (m, 7H), 7.22-7.12 (m, 4H), 7.08-7.02 (m, 3H), 7.27 (d, 2H, J= 8.1 Hz), 6.34 (s, 1H), 2.22 (s, 6H).

13

C NMR (75 MHz, CDCl3) δ: 171.2, 168.1, 140.9, 137.5, 135.6,

135.5, 134.1, 133.4, 132.5, 130.3, 129.7, 129.0, 128.8, 128.4, 128.2, 127.8, 127.3, 92.7, 66.6, 18.5. HRMS (DART+) calculated for C29H26IN2O2 [M+H]+ 561.10389; found 561.10431. N-(2-(tert-butylamino)-2-oxo-1-phenylenethyl)-N-(2-fluorophenyl)-4-iodobenzamide (3j) The compound 3j was synthesized using the following amounts: 2-fluoroaniline (0.62 g, 3.6 mmol), benzaldehyde (0.38 g, 3.6 mmol), 4-iodobenzoic acid (0.89 g, 3.6 mmol) and tert-butyl isocyanide (0.30 g, 3.6 mmol) and purified by flash column chromatography (eluent 80:20 hexane/EtOAc). The product was obtained as a white solid (1.38 g, 72 %, m.p. 178–180 °C). IRνmax: 3310, 2969, 1656, 1624, 1551, 1360 cm-1. 1H NMR (300 MHz, CDCl3) δ: 7.48 (d, 2H, J= 6.3 Hz), 7.23-7.19 (m, 5H), 7.0.3-7.69 (m, 4H), 6.67 (t, 2H, J= 7.8, 15.3 Hz), 6.15 (s, 1H), 5.58 (s, 1H), 1.36 (s, 9H).

13

C NMR (75 MHz, CDCl3) δ: 170.2, 168.4, 162.9, 159.6, 136.8,

136.5, 136.4, 135.4, 134.5, 132.3, 132.2, 130.2, 130.1, 128.6, 115.4, 115.1, 96.0, 66.2, 51.8, 28.6. HRMS (DART+) calculated for C25H25FIN2O2 [M+H]+ 531.0944; found 531.0935.


25


Page 26 of 35

N-(2-(tert-butylamino)-2-oxo-1-phenylethyl)-N-(2-iodophenyl)benzamide (3k) The compound 3k was synthesized using the following amounts: 2-iodoaniline (0.72 g, 3.2 mmol), benzaldehyde (0.34 g, 3.2 mmol), benzoic acid (0.40 g, 3.2 mmol) and tert-butyl isocyanide (0.27 g, 3.2 mmol) and purified by flash column chromatography (eluent 80:20 hexane/EtOAc). The product was obtained as a white solid (1.11 g, 68 %, m.p. 150–152 °C). IRνmax: 3340, 2970, 1674, 1626, 1469, 1353 cm-1. 1H NMR (300 MHz, CDCl3) δ: 7.95 (d, 1H, J= 7.9 Hz), 7.47 (d, 3H, 7.3 Hz),7.36 (t, 3H, J= 6.2 Hz), 7.22-7.07 (m, 7H), 6.68 (t, 1H, J= 7.6 Hz), 6.16 (s, 1H), 1.39 (s, 7H). 13C NMR (75 MHz, CDCl3) δ: 170.8, 169.0, 142.2, 139.2, 136.1, 133.7, 132.9, 131.1, 130.1, 129.6, 129.2, 129.1, 128.9, 128.5, 128.4, 128.2, 128.1, 127.9, 127.5, 127.2, 103.6, 66.2, 51.8, 28.7. HRMS (DART+) calculated for C25H26IN2O2 [M+H]+ 513.1038; found 513.1033. N-(2-(tert-butylamino)2-oxo-1-phenylethyl)-N-(3-iodophenyl)benzmide (3l) The compound 3l was synthesized using the following amounts: 3-iodoaniline (0.72 g, 3.2 mmol), benzaldehyde (0.34 g, 3.2 mmol), benzoic acid (0.40 g, 3.2 mmol) and tert-butyl isocyanide (0.27 g, 3.2 mmol) and purified by flash column chromatography (eluent 80:20 hexane/EtOAc). The product was obtained as a white solid (1.59 g, 97 %, m.p. 159–161 °C). IRνmax: 3320, 3059, 2968, 1655, 1631, 1551, 1448, 1358, 1253 cm-1. 1H NMR (300 MHz, CDCl3) δ: 7.43-7.09 (m, 12H), 6.98 (d, 1H, J= 7.9 Hz), 6.69 (t, 1H, J= 7.7 Hz), 6.12 (s, 1H), 5.79 (s, 1H), 1.39 (s, 9H).

13

C NMR (75 MHz, CDCl3) δ: 171.0, 168.5, 142.3, 139.0, 136.0, 135.7,

134.6, 130.1, 130.0, 129.7, 129.5, 128.7, 128.6, 128.5, 127.8, 92.8, 66.8, 51.8, 28.7. HRMS (DART+) calculated for C25H26IN2O2 [M+H]+ 513.1038; found 513.1043. N-benzyl-N-(2-(tert-butylamino)-2-oxo-1-phenylethyl)-4-iodobenzamide (3m)


26

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The compound 3m was synthesized using the following amounts: benzylamine (0.51 g, 4.8 mmol), benzaldehyde (0.51 g, 4.8 mmol), 4-iodobenzoic acid (1.2 g, 4.8 mmol) and tert-butyl isocyanide (0.4 g, 4.8 mmol) and purified by flash column chromatography (eluent 90:10 hexane/EtOAc). The product was obtained as a white solid (1.79 g, 71 %, m.p. 155-156 °C). IRνmax: 3306, 1659, 1638, 1545, 1438, 1410 cm-1. 1H NMR (300 MHz, CDCl3) δ: 7.67 (s, 1H), 7.47-7.08 (m, 10H), 6.98 (s, 1H), 5.51 (s, 1H), 4.72 (d, 1H, J= 17.1 Hz), 4,44, (d, 1H, J=14.5 Hz), 1.32 (s, 9H). 13C NMR (75 MHz, CDCl3) δ: 172.3, 168.2, 137.6, 135.8, 129.7, 128.9, 128.7, 128.4, 128.3, 126.9, 107.0, 5.7, 28.6. HRMS (DART+) calculated for C26H28IN2O2 [M+H]+ 527.11954; found 527.11972. N-benzyl-N-(2-(tert-butylamino)-2-oxo-1-phenylethyl)-2-iodobenzamide (3n) The compound 3n was synthesized using the following amounts: benzylamine (0.43 g, 4.0 mmol), benzaldehyde (0.42 g, 4.0 mmol), 2-iodobenzoic acid (1.0 g, 4.0 mmol) and tert-butyl isocyanide (0.33 g, 4.0 mmol) and purified by flash column chromatography (eluent 80:20 hexane/EtOAc). The product was obtained as a white solid (1.69 g, 82 %, m.p. 132–135 °C). IRνmax: 3304, 3029, 2931, 1659, 1638, 1547, 1408 cm-1. 1H NMR (300 MHz, CDCl3) δ: 7.737.66 (m, 2H), 7.44-7.25 (m, 7H), 7.15-7.09 (m, 4H), 7.02-6.93 (m, 2H), 5.53 (s, 1H), 4.71 (d, 1H, J= 16.6 Hz), 4.43 (d, 1H, J= 16.6), 1.31 (s, 9H).

13

C NMR (75 MHz, CDCl3) δ: 171.5, 168.3,

138.7, 138.5, 135.6, 135.1, 130.1, 129.8, 129.2, 129.0, 128.8, 128.4, 128.1, 127.0, 125.7, 94.3, 51.8, 28.69. HRMS (EI+) calculated for C26H27IN2O2 [M]+ 526.1117; found 526.1125. N-benzyl-N-(2-(cyclohexylamino)-2-oxo-1-phenylethyl)-2-iodobenzamide (3o) The compound 3o was synthesized using the following amounts: benzylamine (0.29 g, 2.7 mmol), benzaldehyde (0.29 g, 2.7 mmol), 2-iodobenzoic acid (0.68 g, 2.7 mmol) and cyclohexyl


27


Page 28 of 35

isocyanide (0.29 g, 2.7 mmol) and purified by flash column chromatography (eluent 80:20 hexane/EtOAc). The product was obtained as a white solid (0.71 g, 47 %, m.p. 121-124 °C). IRνmax: 3299, 3029, 2924, 1675, 1607, 1548, 1424 cm-1. 1H NMR (300 MHz, CDCl3) δ: 7.837.59 (m, 2H), 7.47-7.23 (m, 6H), 7.15 (m, 3H), 7.04-6.93 (m, 2H), 5.53 (s, 1H), 4.68 (d, 1H, J= 16.5 Hz), 4.45-4.40 (m, 1H), 3.89-3.71 (m, 1H), 1.98-1.70 (m, 2H), 1.68-1.51 (m, 3H), 1.40-1.23 (m, 2H), 1.19-0.92 (m, 3H).

13

C NMR (75 MHz, CDCl3) δ: 171.5, 168.2, 138.7, 138.3, 135.7,

134.7, 130.1, 129.8, 129.0, 128.9, 128.5, 127.1, 125.6, 94.1, 64.4, 52.6, 48.8, 32.8, 25.5, 24.8. HRMS (EI+) calculated for C28H29IN2O2 [M]+ 552.1274; found 552.1268. N,N´-((1,4-phenylenebis(ethyne-2,1-diyl))bis(4,1-phenylene))bis(N-(2-(cyclohexylamino)-2oxo-1-phenylethyl)benzamide) (1a) The compound 1a was synthesized using the following amounts: Ugi adduct (0.4 g, 0.740mmol), 1,4-diethynylbenzene (0.047g, 0.037mmol), PdCl2(PPh3)2 (0.052 g, 0.074 mmol) and CuI (0.0071g, 0.037 mmol), and purified by flash column chromatography (eluent 7:3 hexane/EtOAc). The product was obtained as a yellow solid (0.23 g, yield 33 %, m. p. 133-135 ºC). IRνmax: 3055, 2922, 1646, 1589, 1436 cm-1. 1H NMR (300 MHz, CDCl3) δ: 7.48-7.08 (m, 28H), 6.99 (d, 4H, J= 7.01 Hz), 6.27 (s, 2H), 5.87 (d, 1H, J= 8.1 Hz), 4.02-3.74 (m, 1H), 1.991.88 (m, 4H), 1.70-1.56 (m, 6H), 1.37-1.27 (m, 4H), 1.17-1.03 (m, 6H).

13

C NMR (75 MHz,

CDCl3) δ 171.0, 168.4, 141.2, 135.8, 134.5, 132.3, 131.4, 131.3, 130.3, 130.1, 129.5, 128.5, 128.4, 127.6, 122.8, 121.4, 91.3, 90.5, 89.7, 89.5, 66.1, 48.8, 32.7, 25.4, 24.6. HRMS (FAB+) calculated for C64H58N4O4 [M+H]+ 946.4458; found 946.4454. N,N´-((1,4-phenylenebis(ethyne-2,1-diyl))bis(4,1-phenylene))bis(N-(2-(tert-butylamino)-2oxo-1-phenylethyl)benzamide) (1b)


28

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The compound 1b was synthetized using the following amounts: Ugi adduct (0.4 g, 0.780 mmol), 1,4-diethynylbenzene (0.049g, 0.390 mmol), PdCl2(PPh3)2 (0.055 g, 0.078 mmol) and CuI (0.039g, 0.039 mmol), and purified by flash column chromatography (eluent 7:3 hexane/EtOAc). The product was obtained as a yellow oil (0.082 g, yield 12 %, m. p. 124-126 ºC). IRνmax: 3329, 2963, 2922, 1683, 1634, 1513 cm-1. 1H NMR (300 MHz, CDCl3) δ: 7.37 (s, 2H), 7.32 (d, 2H, J= 6.0 Hz), 7.26-7.22 (m, 5H), 7.20-7.11 (m, 5), 7.49 (d, 2H, J= 6.0 Hz), 6.17 (s, 1H), 5.73 (s, 1H), 1.38 (s, 9H).

13

C NMR (75MHz, CDCl3) δ: 171.0, 168.5, 141.3, 135.8,

134.7, 132.4, 131.5, 131.4, 130.3, 130.1, 129.6, 128.5, 128.4, 127.7, 122.8, 121.4, 90.6, 89.7, 66.6, 51.7, 28.6. HRMS (DART) calculated for C60H55N4O4 [M+H]+ 895.42233; found 895.42274. N,N´-((1,4-phenylenebis(ethyne-2,1-diyl))bis(4,1-phenylene))bis(N-(2-(tert-butylamino)-2oxo-1-phenylethyl)-4-chloro-3-nitrobenzamide) (1c) The compound 1c was synthesized using the following amounts: Ugi adduct (0.45 g, 0.760 mmol), 1,4-diethynylbenzene (0.048 g, 0.380 mmol), PdCl2(PPh3)2 (0.054 g, 0.077 mmol) and CuI (0.0072 g, 0.038 mmol), and purified by flash column chromatography (eluent 7:3 hexane/EtOAc). The product was obtained as a yellow solid (0.376 g, yield 47 %, m. p. 134-136 ºC). IRνmax: 3066, 2961, 2923, 1642, 1536, 1514, 1343 cm-1. 1H NMR (300 MHz, CDCl3) δ: 7.92 (s, 1H), 7.42-7.39 (m, 3H), 7.30 (d, 1H, J= 8.4 Hz), 7.27-7.18 (m, 7H), 7.02 (s, 2H), 6.15 (s, 1H), 5.52 (s, 1H), 1.37 (s, 9H). 13C NMR (75 MHz, CDCl3) δ 168.0, 167.2, 147.1, 139.9, 135.8, 133.9, 132.8, 131.9, 131.5, 131.3, 130.5, 130.3, 128.9, 128.7, 128.3, 126.1, 122.8, 122.6, 90.4, 90.2, 66.6, 52.0, 28.6. HRMS (FAB+) calculated for C60H51Cl2N6O8 [M+H]+ 1053.3145; found 1053.3142.


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4,4-(1,4-phenylenebis(ethyne-2,1-diyl))bis(N-benzyl-N-(2-(tert-butylamino)-2-oxo-1phenylethyl)benzamide) (1m) The compound 1m was synthesized using the following amounts: Ugi adduct (0.40 g, 0.760 mmol), 1,4-diethynylbenzene (0.048 g, 0.380 mmol), PdCl2(PPh3)2 (0.054 g, 0.077 mmol) and CuI (0.0072 g, 0.038 mmol), and purified by flash column chromatography (eluent 7:3 hexane/EtOAc). The product was obtained as a yellow solid (0.186 g, yield 27 %, m. p. 160-162 ºC). IRνmax: 3058, 3030, 2925, 1691, 1623, 1604, 1549, 1497, 1407 cm-1. 1H NMR (300 MHz, CDCl3) δ: 7.70-7.64 (m, 3H), 7.55-7.46 (m, 9H), 7.28 (d, 2H, J= 9.0 Hz), 7.13 (s, 2H), 6.99 (s, 2H), 5.52 (s, 1H), 4.74 (d, 1H, J= 17.4 Hz), 4.46 (d, 1H, J= 16.8 Hz), 1.32 (s, 9H). 13C NMR (75 MHz, CDCl3) δ: 172.5, 168.3, 136.1, 135.0, 131.6, 131.5, 129.6, 128.8, 128.6, 128.2, 126.9, 126.8, 124.4, 122.9, 90.6, 90.4, 51.6, 29.6, 28.5. HRMS (DART+) calculated for C62H59N4O4 [M+H]+ 923.45363; found 923.45294. 2,2’-(1,4-phenylenebis(ethyne-2,1-diyl))bis(N-benzyl-N-(2-(tert-butylamino)-2-oxo-1phenylethyl)benzamide) (1n) The compound 1n was synthesized using the following amounts: Ugi adduct (0.20 g, 0.38 mmol), 1,4-diethynylbenzene (0.024 g, 0.19 mmol), PdCl2(PPh3)2 (0.027 g, 0.038 mmol) and CuI (0.0036 g, 0.019 mmol), and purified by flash column chromatography (eluent 7:3 hexane/EtOAc). The product was obtained as a yellow solid (0.099 g, yield 28 %, m.p. 99–102 °C). IRνmax: 3314, 3060, 2918, 2849, 1679, 1622, 1448, 1361 cm-1. 1H NMR (300 MHz, CDCl3) δ: 7.66 (s, 2H), 7.58-7.24 (m, 20H), 7.19-7.11 (m, 6H), 6.69 (s, 4H), 5.55 (s, 4H), 4.78 (d, 2H, J= 16.4 Hz), 4.50 (d, 2H, J=16.4 Hz), 1.37 (s, 18H).

13

C NMR (75 MHz, CDCl3) δ: 172.2, 168.3,


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Page 31 of 35 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


136.8, 135.1, 132.6, 131.6, 129.7, 128.8, 128.6, 128.3, 127.1, 126.9, 126.5, 90.4, 89.9, 51.7, 28.6. HRMS (FAB+) calculated for C62H59N4O4 [M+H]+ 923.4536; found 923.4541. 2,2’-(1,4-phenylenebis(ethyne-2,1-diyl))bis(N-benzyl-N-(2-(tert-butylamino)-2-oxo-1phenylethyl)benzamide (1l) The compound 1l was synthesized using the following amounts: Ugi adduct (0.28 g, 0.55 mmol), 1,4-diethynylbenzene (0.035 g, 0.28 mmol), PdCl2(PPh3)2 (0.038 g, 0.055 mmol) and CuI (0.0052 g, 0.027 mmol), and purified by flash column chromatography (eluent 7:3 hexane/EtOAc). The product was obtained as a yellow solid (0.227 g, yield 47 %, m.p. 118–120 °C). IRνmax: 3315, 3064, 2965, 1683, 1634, 1594, 1449, 1330 cm-1. 1H NMR (300 MHz, CDCl3) δ: 7.44 (s, 1H), 7.38-7.17 (m, 26H), 6.98 (t, 2H, J=7.5 Hz), 6.12 (s, 2H), 5.78 (2H), 1.40 (s, 18H).

13

C NMR (75 MHz, CDCl3) δ: 171.0, 168.6, 141.6, 135.8, 134.8, 133.0, 132.4, 131.5,

130.3, 129.6, 128.6, 128.5, 128.4, 127.8, 123.3, 122.9, 90.4, 89.5, 67.2, 51.7, 28.6. HRMS (FAB+) calculated for C60H54N4O4 [M+H]+ 894.4145; found 894.4129. Autor Information Corresponding Authors *L. D. M. e-mail: [email protected] *B. R. M. e-mail: [email protected] Notes The authors declare no competing financial interests. ORCID Ma. Carmen García-González: 0000-0003-1359-3362


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Andrés Aguilar-Granda: 0000-0003-4435-5316 Angel Zamudio-Medina: 0000-0003-4920-3768 Luis D. Miranda: 0000-0003-0342-8160 Braulio Rodríguez-Molina: 0000-0002-1851-9957 Acknowledgments We thank the financial support from PAPIIT-UNAM (IA201117) and CONACYT (238913). A.A.-G. thanks to CONACYT (scholarship 279212). We thank B. Quiroz, A. Peña, E. Huerta (NMR), L. Velasco and J. Pérez (MS), R. Patiño (IR) for technical support. We thank Dr. Arturo Jimenez for his valuable scientific discussions. We also thank Dr. Alejandro Dorazco for the fluorescence experiments at low temperature. Supporting Information The Supporting Information is available free of charge on the ACS Publications website at DOI: Synthetic procedures, spectroscopic

1

H and

13

C NMR data for all compounds, DLS

measurements, VT 1H NMR data, UVvis and emission spectra of all compounds. References

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Synthesis of Structurally Diverse Emissive Molecular Rotors with Four

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