Samaneh Koosha,
Sedigheh Alavinia and
Ramin Ghorbani-Vaghei*
Department of Organic Chemistry, Faculty of Chemistry, Bu-Ali Sina University, 6517838683, Hamadan, Iran. E-mail: rgvaghei@yahoo.com; ghorbani@basu.ac.ir; Fax: +98-8138380709; Tel: +98-8138380709
First published on 12th April 2023
As a significant class of synthetic and natural products with multiple biological activities, quinolines are used in medical and electronic devices. In this study, a novel method is presented to synthesize 2,4-diarylquinoline derivatives via a simple one-pot multicomponent reaction between phenylacetylenes, aniline derivatives, and aldehydes in CH3CN using IRMOF-3/PSTA/Cu. Notably, polymer/MOF is stabilized through a reaction between a sulfonamide-triazine-based porous organic polymer [poly (sulfonamide-triazine)](PSTA) and an amino-functionalized zinc metal–organic framework (IRMOF-3). Next, the prepared nanocomposites (IRMOF-3/PSTA) are modified using copper iodide nanoparticles (CuI NPs). Overall, the high product yields, facile recovery of nanocatalysts, short reaction times, and broad substrate range make this process environmentally friendly, practical, and economically justified.
In addition, metal–organic frameworks (MOFs), as a new category of mesoporous compounds, have numerous found applications in gas storage, catalytic processes, drug delivery, encapsulating materials, supercapacitors, and heavy metal absorbents.10–13 MOFs not only have a higher level of activation and stability than other classes of porous materials but also can change the morphology and size of cavities.14 Accordingly, this feature has become an advantage in terms of separation and greater selectivity in their applications.15–17
MOFs are promising inorganic compounds that can be incorporated into polymer matrices to synthesize polymer/MOF nanocomposites.18–21 In this regard, isoreticular organometallic framework-3 (IR-MOF-3) is an important MOF with a cubic framework22–26 with a structure containing a 2-aminoterephthalic acid linker and a Zn4O cluster.27 As a result, this structure has free NH2 functional groups not bound to tetragonal ZnO4. These features allow IR-MOF-3 to be modified with various organic and organometallic compounds (Fig. 2).28,29 Mesoporous polysulfonamides, among others, are compounds of great interest because of their efficiency in preparing heterogeneous catalysts and their use in medicinal chemistry.30 Mesoporous polysulfonamides have high chemical stability, high surface area, and low skeletal density.30,31 In this sense, a new organic support system consisting of porous sulfonamide triazine-based (PSTA) polymers was prepared using the silica template method (Fig. 2).
MOF/polymer nanocomposites are suitable candidates, functioning as ligands and forming metal complexes, to deposit metal nanoparticles in their substrate regarding their extraordinary features in structural engineering and regular architecture.32–34 These compounds have the potential to form complexes because of oxygen groups and nitrogen presence. Therefore, they can be used as excellent support in applications related to catalysis.10,18,35 Additionally, the key points in using these nanocomposites as support in heterogeneous catalytic systems are the high specific surface area and easy separation from the reaction mixture.36
According to the above-mentioned points, this research aimed at designing and characterizing a novel hybrid crystalline/amorphous material composed of IRMOF-3 and PSTA that offers the advantages of both materials. Moreover, when these agents are combined, it would improve the thermal stability, binding sites, and metal loading levels of the prepared supports. Significantly, the CuI NPs were successfully decorated with the prepared supports (IRMOF-3/PSTA/Cu). Nanocatalysts were successfully incorporated into ternary reactions to prepare new 2,4-diarylquinolines.
Quinolines are specific heterocyclic pharmacophores with diverse medicinal chemistry and several interesting pharmacological and therapeutic characteristics.37–39 They are also used as the core moieties to prepare many well-known drugs with antifungal, antioxidant, and antituberculous activity (Fig. 1).40–43 Regarding strategies to synthesize quinoline derivatives, some routes possess specific advantages, i.e., applying safer reagents and solvents, atom economy, being environmentally friendly, and reducing waste production.44,45 The method proposed in our work (Scheme 1) is a one-step reaction with an easy purification process and simple recrystallization that takes advantage of the economy of solvents and atoms.
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Fig. 1 The quinoline (1), the naturally-occurring compound quinine (II), and synthetic chloroquine (III) structures. |
A prominent peak appeared at 3000–4000 cm−1 corresponding to the amino group of the stretching vibration.47 The sharp bands from 1682 to 1344 cm−1 signified CC stretching vibrations of a benzene ring and symmetric and asymmetric modes of the dicarboxylate groups.48 Furthermore, the peaks at 1101 and 830 cm−1 correspond to the aromatic C–H bending vibrations.49 The absorption peak at 681 cm−1 is due to the metal–oxygen bond of Zn–O (Fig. 3a).16,50 Regarding the SiO2/PSTA sample, the weak peak at 812 cm−1 and the sharp and broad absorption peaks at 1099 cm−1 are attributed to symmetric and asymmetric Si–O–Si bond stretches, respectively.51 Vibrational bands observed at 1160 and 1338 cm−1 represent the presence of a sulfone bridge in the catalyst.52 Absorption peaks at 1660, 1680, and 1645 cm−1 are related to the melamine presence in the studied structure (Fig. 3b).53,54 We did not observe SiO2 NPs peak in the FT-IR spectra porous PSTA because of the s selective removal of the template (Fig. 3c). After the hybridization of IRMOF-3 with porous PSTA, the characteristic absorption bands (as previously described) were observed (Fig. 3d). Adding CuI NPs to the structure of IRMOF-3/PSTA significantly changed the FTIR spectra (1685 vs. 1665 cm−1). Moreover, the bands at 3344 cm−1 and 3248 cm−1 corresponding to the NH2 stretching vibrations shifted to a lower wavenumber compared with 3355 cm−1 and 3257 cm−1 due to the NH2 stretching vibrations of IRMOF-3/PSTA/Cu (Fig. 3e).
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Fig. 3 FT-IR spectra of IRMOF-3 (a), SiO2/PSTA (b), porous PSTA (c), IRMOF-3/PSTA (d), and IRMOF-3/PSTA/Cu (e). |
XRD measurements were performed to evaluate the crystal structures of the prepared porous IRMOF-3/PSTA/Cu and PSTA (Fig. 4). The XRD pattern of the prepared porous PSTA revealed a high degree of crystallization and characteristic peaks of sulfonamides and triazines at 2θ = 17.34°, 24.04°, and 29.99° 65. Furthermore, no peaks for SiO2 NPs were observed in the XRD pattern of porous PSTA (Fig. 4a). As can be seen from the XRD pattern of the final catalyst (Fig. 4b), the XRD pattern of the synthesized IRMOF-3/PSTA/Cu catalyst has all the characteristic peaks of IRMOF-3 (2θ = 25.54°, 42.24°, and 49.89°).55 Moreover, porous PSTA (2θ = 18.19°, 23.94°, 29.99°) and CuI NPs (2θ = 29.54°, 61.29°)31 demonstrated successful hybridization and inorganic and organic phases in nanocomposites. Herein, the peak intensity of PSTA decreases at 2θ = 18.19°, 23.94° and 29.99°. This change is attributed to the interaction between PSTA and IRMOF-3. Besides, using the Scherer equation, the size of the IRMOF-3/PSTA/Cu nanocomposite crystal was calculated as 3.56 nm, indicating the obtained crystal structure of IR-MOF-3.
FESEM was performed to investigate the size and surface morphology of IRMOF-3, porous PSTA, IRMOF-3/PSTA, and IRMOF-3/PSTA/Cu (Fig. 5). A well-distributed, nearly cubic, and uniform nanostructure with a grain size of 75 ± 10 nm was observed in the synthesized IRMOF-3 (Fig. 5A). In addition, FESEM images of PSTA (Fig. 5B) were captured for SiO2/PSTA nanocomposites using the selective removal of the silica template. As can be seen, the prepared sample has a 3D porous, regular network with numerous spherical nanopores. The FESEM image of IRMOF-3/PSTA indicates the spherical structure of PSTA developed on IRMOF-3's surface. Moreover, they exhibited a complex and porous nature (Fig. 5C). Notably, the spherical CuI particle distribution on IRMOF-3/PSTA was evident in the FESEM images of the prepared nanocatalysts (Fig. 5D).
The size distribution of IRMOF-3/PSTA/Cu was investigated using transmission electron microscopy (TEM) (Fig. 6). The TEM images of IRMOF-3/PSTA/Cu show a nanocomposite structure.
The EDX analysis was performed to determine the elemental composition of the IRMOF-3/PSTA/Cu NPs, which confirmed the presence of catalytic components (Fig. 7). Elemental mapping studies of IRMOF-3/PSTA/Cu NPs showed a uniform distribution of carbon, copper, oxygen, iodide, nitrogen, sulfur, and zinc components in the fabricated structure (Fig. 8). In addition, the ICP-AES analysis of IRMOF-3/PSTA/Cu showed 0.88 mmol g−1 Cu.
In this research, TGA was performed to investigate the stability of the prepared catalyst (Fig. 9). The TGA curve of IRMOF-3/PSTA/Cu shows three stages of degradation. Through steps 1, 2, and 3, this composite decomposes at 59.39, 382, and 546.87 °C, respectively, typically losing 62.63% of its weight. The first step, starting at 25–236.4 °C, is attributed to solvent removal and thermal condensation of melamine to produce NH3 and carbon nitride (CN).46 Step 2, starting at 236.4–382 °C, is due to the decomposition of the polymer backbone. Finally, step 3, i.e., from 382 to 546.87, is attributed to the MOF backbone (Fig. 9).
BET analysis was carried out on the N2 adsorption/desorption isotherms of IRMOF-3, PSTA, and IRMOF-3/PSTA nanostructures. A characteristic type IV H4 hysteresis loop was observed in the synthesized compound, indicating an ordered mesoporous structure (Fig. 10). The specific surface areas of IRMOF-3, porous PSTA, and IRMOF-3/PSTA are 34.96, 2.67, and 19.05 m2 g−1, respectively (Table 1). As expected, the observed decrease in the synthesized composites is mainly due to the modification of IRMOF-3 by porous PSTA.
Parameter | IRMOF-3/PSTA | PSTA | IRMOF-3 |
---|---|---|---|
as (m2 g−1) | 34.96 | 2.67 | 19.05 |
Vm (cm3 (STP) g−1) | 11.31 | 0.81 | 6.1 |
Vp (cm3 g−1) | 0.36 | 0.017 | 0.18 |
rp (nm) | 53.04 | 1.64 | 71.9 |
ap (m2 g−1) | 34.54 | 5.64 | 19.52 |
The atomic oxidation states and chemical compositions of IRMOF-3/PSTA/Cu were investigated using XPS. According to the XPS analysis (Fig. 11a), the basic elements in IRMOF-3/PSTA/Cu are Cu, I, C, O, N, S, and Zn, which is consistent with the EDS analysis results. According to Fig. 11b, the absorption peaks of C1 at binding energies of 287.7 eV, 285.1 eV, and 283.8 eV are assigned to CC, C–N, and O
C–O, respectively, corresponding to amino terephthalate ligands. Fig. 11c indicates the spectrum of O 1s. Peaks at 530.0 eV and 531.5 eV correspond to M–O (M = Zn, Cu) and O
C–O, respectively. Two peaks at 399.0 eV and 400.8 eV correspond to the functional groups C–NH2 and C
N, respectively (Fig. 11d). The observed I 3d peaks in Fig. 11e are characteristic of CuI NPs (Fig. 11e). Moreover, the Cu 2p spectrum indicates two strong peaks at 935.3 eV and 955.0 eV, related to Cu 2p3/2 and Cu 2p1/2 (Fig. 11f), respectively. This observation is a strong reason to prove the interaction of Cu(I) and IRMOF-3/PSTA. The peaks shown in Fig. 11g at 1044.9 eV and 1022.1 eV for Zn 2p in IRMOF-3 are characteristics of Zn 2p1/2 and Zn 2p3/2, respectively. Accordingly, it is confirmed that introducing porous PSTA and CuI NPs into IRMOF-3 resulted in successful surface functionalization.
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Fig. 11 XPS spectra of IRMOF-3/PSTA/Cu: (a) survey, (b) C 1s, (c) O 1s, (d) N 1s, (e) I I 3d, (f) Cu 2p, and (g) Zn 2p. |
Entry | Cat. (mg) | Solvent | Temperature (°C) | Time (h) | Yieldb (%) |
---|---|---|---|---|---|
a Reaction condition: p-anisidine (1.0 mmol), phenylacetylene (1.2 mmol), benzaldehyde (1.1 mmol), in CH3CN (2 mL).b Isolated yields. | |||||
1 | IRMOF-3/PSTA/Cu (5) | CH3CN | 80 | 1 | 81 |
2 | IRMOF-3/PSTA/Cu (10) | CH3CN | 80 | 1 | 90 |
3 | IRMOF-3/PSTA/Cu (20) | CH3CN | 80 | 1 | 90 |
4 | IRMOF-3/PSTA/Cu (10) | Toluene | 80 | 1 | 62 |
5 | IRMOF-3/PSTA/Cu (10) | EtOH | 80 | 1 | 23 |
6 | IRMOF-3/PSTA/Cu (10) | DMF | 80 | 1 | 43 |
7 | IRMOF-3/PSTA/Cu (10) | CH3Cl3 | 80 | 1 | 29 |
8 | IRMOF-3 (10) | CH3CN | 80 | 1 | 55 |
9 | UiO-66-NH2 (10) | CH3CN | 80 | 1 | 35 |
10 | Zn(NO3)2·6H2O (10) | CH3CN | 80 | 1 | Trace |
11 | CuI NPs (10) | CH3CN | 80 | 1 | 51 |
12 | IRMOF-3/PSTA (10) | CH3CN | 80 | 1 | 60 |
13 | PSTA/Cu (10) | CH3CN | 80 | 1 | 66 |
14 | IRMOF-3/Cu (10) | CH3CN | 80 | 1 | 80 |
15 | IRMOF-3/PSTA/Cu (10) | CH3CN | 60 | 1 | 73 |
The generality and range of reactions were investigated for various anilines under optimal conditions (Table 3). Based on the obtained results, aniline's electron-withdrawing groups enhanced the IRMOF-3/PSTA supported Cu-catalyzed domino reactions with higher reactivity than those containing electron-donating groups, leading to higher yields (4b vs. 4e and 4h). The Diels–Alder reaction is the so-called inverse electron claim when the dienophile has an electron-withdrawing group, and the diene possesses an electron-donating group. The reaction with the methyl group of aniline (4i) gave similar yields as with the methoxy group (4b). A comparison of these results with the nitro group (4h) and bromide and chloride groups (4a, 4c, 4e) shows that the yield and reaction rate are functions of the EWG strength. The explanation is that the bromo group is less electron-donating than the nitro group, resulting in lower yields. In this study, we prepared new quinoline derivatives, which are the first to be reported.
Entry | Aniline | Product | Time (min) | Yieldb (%) | Melting point | |
---|---|---|---|---|---|---|
Measured | Reported (ref.) | |||||
a Reaction condition: phenyl acetylene (1.2 mmol), IRMOF-3/PSTA/Cu (0.01 g, 0.88 mol%), aniline derivatives (1.0 mmol), and benzaldehyde (1.1 mmol) in CH3CN (2 mL) was heated at 80 °C.b Isolated yield. | ||||||
1 | ![]() |
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90 | 82 | 162–164 | New |
2 | ![]() |
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180 | 76 | 119–120 | 121–122 (ref. 56) |
3 | ![]() |
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85 | 84 | 147–149 | 150–152 (ref. 57) |
4 | ![]() |
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75 | 85 | 155–157 | New |
5 | ![]() |
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85 | 80 | 134–136 | 131–132 (ref. 58) |
6 | ![]() |
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240 | 74 | 80–82 | 81–82 (ref. 59) |
7 | ![]() |
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75 | 83 | 251–253 | New |
8 | ![]() |
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60 | 90 | 262–263 | 265–266 (ref. 60) |
9 | ![]() |
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180 | 78 | 120–122 | 122–123 (ref. 61) |
10 | ![]() |
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120 | 88 | 150–152 | 150–152 (ref. 56) |
The advantages of the produced nanocatalysts are summarized in Table 4. The table compares the properties of various catalytic systems used to produce 2,4-diarylquinolines in the presence of different catalysts. According to these data, the catalytic system presented in this study offers higher efficiency than other systems for this reaction regarding the reaction yield and time. The advantages of IRMOF-3/PSTA/Cu as the catalyst in the system include a less intensive process, a high yield of 92%, and separability and recyclability up to several times, which are difficult to obtain using pure CuI NPs (entry 4).
Scheme 2 shows the mechanism offered for the one-pot preparation of quinoline derivatives catalyzed by IRMOF-3/PSTA/Cu. According to this mechanism, the IRMOF-3/PSTA/Cu catalyst first enhances the activity of phenylacetylene binding to iminium ions generated in situ by the reaction between benzaldehydes and amines. Afterward, phenylacetylene reacts with a Schiff base through a concerted cyclization, i.e., the Diels–Alder reaction, to give the dihydroquinoline. Finally, the target products are formed via oxidation (Scheme 2).64
As shown in Fig. 12, the stability of the catalysts was proved via the characterization by FT-IR and FESEM (90, 90, 88, 87, 85, and 82). The outcomes confirmed the stability of the catalysts as the regeneration data do not exhibit any change after the initial patterns (Fig. 13).
Footnote |
† Electronic supplementary information (ESI) available. See DOI: https://doi.org/10.1039/d3ra01164j |
This journal is © The Royal Society of Chemistry 2023 |