Mohammad Ali
Ghasemzadeh
* and
Boshra
Mirhosseini-Eshkevari
Department of Chemistry, Qom Branch, Islamic Azad University, Post Box: 37491-13191, Qom, I. R. Iran. E-mail: qasemzade.a@gmail.com; ma.ghasemzadeh@iau.ac.ir
First published on 6th November 2023
The creation of an emerging porous structure using the hybridization of UiO-66-NH2-MOF, a zirconium-based metal–organic framework (MOF), with a covalent organic framework (COF) based on terephthaldehyde and melamine (UiO-66-NH2-MOF@COF), was assessed using SEM, XRD, EDX/mapping, FT-IR, BET, and TGA analyses. Using the obtained composite as a potential recoverable heterogeneous nanocatalyst, different aldehydes were condensed with isatoic anhydride and anilines or ammonium acetate under solvent-free conditions to create derivatives of 2,3-dihydroquinazolin-4(1H)-one. Examining the catalytic capabilities of the designed UiO-66-NH2-MOF@COF to efficiently produce 2,3-dihydroquinazolin-4(1H)-ones was a standout activity. Low catalyst loading, simple set-up, outstanding yields, and catalyst recoverability are all benefits of this research.
Likewise, covalent organic frameworks (COFs) are a significant group of 2D or 3D-ordered porous materials composed of organic building blocks linked by reversible covalent bonds.10,11
Outstanding features are exhibited by these porous materials such as good to excellent porosity, large surface area, excellent adsorption abilities, adjustable frameworks, great thermal and chemical stability, highly ordered structures, and low density.12,13 COFs based on network chemistry are made from light elements (O, C, B, N, etc.) via excellent covalent bonding. They have represented superior potential in different usages.14,15 New MOF/COF hybrids integrate the extremely good capabilities of MOF and COF structures, inclusive of excessive crystallinities, excessive porosities, large floor areas, the potential to enhance the structures with purposeful groups, and improved chemical and mechanical stabilities.16,17 Therefore, it is expected that the development of MOF-COF hybrid mesoporous materials could enhance their inherent weak characters and have a synergistic effect to originate multifunctional properties for unique programs. Currently, MOF-COF hybrid resources have been applied to related synthetic approaches using amino-functionalized MOFs to graft imine-based COFs.18,19 Significant interest has been attracted by multi-component reactions (MCRs) in organic syntheses since they can create target products in a single operation with no isolation of intermediates. Thus, energy and reaction times are reduced.20,21 Organic reactions under circumstances without solvent have highly encouraged chemists' attention mainly from the green chemistry aspect. Green chemistry methods are considerable for reducing byproducts, produced waste, and energy costs. Potential MCRs in the absence of solvent conditions using nanostructures as catalysts could improve their efficacy economically and ecologically.22,23
Quinazolin-4-ones are significant bicyclic heterocycles with significant pharmacological and biological properties such as antifungal,24 analgesic,25 antidiabetic,26 antitumor,27 antibacterial,28 anticonvulsant,29 and antihypertensive.30
Because of considerable attention to 2,3-dihydroquinazolin-4(1H)-ones, various approaches were established to produce substituted dihydroquinazolin-4(1H)-ones.31–33 Among the important methods are substances such as isatoic anhydride, and aldehydes exposed to primary amine or ammonium acetate using various catalysts or reagents such as amberlyst-15 microwave-assisted,34 Zn(PFO)2,35 silica-bonded N-propylsulfamic acid (SBNPSA),36p-toluenesulfonic acid,37 silica sulfuric acid,38 ceric ammonium nitrate,39 montmorillonite K-10,40 Ga(OTf)3,41 and ionic liquids.42
In the following of our studies43–47 on the synthesis of novel heterogeneous catalysts, in this research we report how to prepare and use UiO-66-NH2-MOF@COF as a bifunctional acid–base catalyst for the production of 2,3-dihydroquinazolin-4(1H)-ones by ternary condensation between isatoic anhydride, aldehydes, and ammonium acetate or primary amines under solvent-free conditions (Scheme 1).
Spectral data of the new products are given below.
The morphology and particle size of UiO-66-NH2-MOF@COF were evaluated by assessing the prepared sample by FE-SEM (Fig. 1). A spherical shape and nano-scale dimension were represented by FE-SEM images of UiO-66-NH2-MOF@COF. As can be seen from Fig. 1, the particle size of UiO-66-NH2-MOF@COF are approximately in the range of 15 to 45 nm with an average particle size of about 25–35 nm, which is in good agreement with the results calculated using the Scherrer equation.
XRD analysis was utilized to prove the as-synthesized sample crystalline structures. Unambiguous evidence was represented by the coexistence of characteristic diffraction peaks for the COF and UiO-66-NH2 while successfully preparing UiO-66-NH2-MOF@COF. According to Fig. 2, the composite represented robust diffraction peaks allocated to UiO-66-NH2. There were relatively weak characteristic peaks of the COF layer. The obvious diffraction peaks at (111), (200), (311), (222), (400), (420), (511), (600) and (640) correspond to the construction of UiO-66-NH2 consistent with the reported values (Fig. 2).49 It is indicated that the catalyst contains pure phases with no distinctive peaks associated with the impurities. The particle size of UiO-66-NH2-MOF@COF nanoparticles is determined to be about 28 nm using Debye–Scherrer's equation (K = 0.90) which has good agreement with SEM analysis.
The EDX analysis and X-ray mapping of UiO-66-NH2-MOF@COF are illustrated in Fig. 3. The percentage of index elements is represented by the EDX spectrum in UiO-66-NH2-MOF@COF (N = 29.58%, C = 28.55%, Zr = 11.69%, and O = 30.17%) confirming the resultant UiO-66-NH2-MOF/COF nanostructure. There was no impurity in the prepared nanocomposite based on the elemental distribution of C, N, O, and Zr in Fig. 3. Besides, within UiO-66-NH2-MOF@COF, the uniform dispersion of components was revealed. Fig. 3 displays the uniform outline of the elements in the prepared nanostructure.
Fig. 4 indicates the FT-IR spectra of the UiO-66-NH2-MOF@COF and UiO-66-NH2 nanostructure. The peak at around 764 cm−1 originated from Zr–O bonds in UiO-66-NH2 (refs. 50 and 51). Two peaks at 1185 and 1655 cm−1 correspond to symmetric and asymmetric stretching vibrations of the carboxylate COO− ion.52 The peak at 1384 cm−1 might denote the C–N tensile vibrations. There are two characteristic peaks at 3334 and 3438 cm−1, which show the existence of NH2 and 2-aminoterephthalic acid moieties in UiO-66-NH2. The construction of the triazine cycle presents robust stretching vibrations at 1495 cm−1 and 1568 cm−1 (CN) in the spectrum of UiO-66-NH2-MOF@COF reflecting that melamine was successfully incorporated into the framework.
To calculate the pore volume and BET surface area, N2 adsorption was used along with the pore size distribution patterns determined from the desorption branch of the N2 isotherm using the Barrett–Joyner–Halenda (BJH) model (Fig. 5). The available surface area was 1028 m2 g−1 according to the BET plots. Besides, the pore volume of the cavities in UiO-66-NH2-MOF@COF was 0.325 cm3 g−1 (Fig. 5a). As seen in Fig. 5b, the type IV adsorption–desorption isotherm with a hysteresis loop denotes the designating of its mesoporous features.53 As shown in Fig. 5c, the pore-size distribution of the UiO-66-NH2-MOF@COF nanocomposite is 1.85 nm from the N2 isotherm desorption branch through the BJH model, which signifies the coexistence of structural pores along with inter-particle pores.
Fig. 5 BET-plot of UiO-66-NH2-MOF@COF (a), adsorption/desorption of UiO-66-NH2-MOF@COF (b), and BJH-plot of UiO-66-NH2-MOF@COF (c). |
The TGA analyses were utilized to assess the stability and resistance of the nanocomposite against thermal decomposition. The loss of weight of UiO-66-NH2-MOF@COF followed by increasing the temperature is shown in Fig. 6. UiO-66-NH2-MOF@COF revealed three-stage weight losses in the TGA curve. The first weight loss at 0–150 °C (25%) represents the loss of solvents and adsorbed water from the framework while the second one at 250–350 °C (40%) denotes the degradation of UiO-66-NH2 in the structure of UiO-66-NH2-MOF@COF.54 Ultimately, the third weight loss step at >400 °C (16%) shows the COF structure collapse.55
Subsequently, we assessed the effectiveness of the catalyst in synthesizing some heterocyclic compounds including 2,3-dihydroquinazolin-4(1H)-ones. We initially chose the reaction of aniline, isatoic anhydride, and 4-nitrobenzaldehyde as a model study evaluating the optimized reaction conditions (Scheme 3). We explored the influences of various catalysts, solvents, and temperatures.
The present research is significant because of the astonishingly catalytic performance of our catalyst compared to other catalysts such as ZnO, CuI, IRMOF-3, and UiO-66-NH2, which were investigated in the model reaction using each catalyst (0.01 g) separately. The results in Fig. 7 show that the best outcomes were achieved (98% yield within 10 min) using UiO-66-NH2-MOF@COF in the absence of any solvent (Fig. 7).
In continuation, we examined the influence of different quantities of UiO-66-NH2-MOF@COF in the model study. Table 1 shows the results obtained from the model study for determining the best amount of the catalyst in the range of 80–120 °C. The best outcomes were achieved using 0.007 g of UiO-66-NH2-MOF@COF at 110 °C.
Entry | Catalyst amount (g) | Temp. (oC) | Time (min) | Yieldb (%) |
---|---|---|---|---|
a Reaction conditions: UiO-66-NH2-MOF@COF, isatoic anhydride (1 mmol), 4-nitrobenzaldehyde (1 mmol), and aniline (1 mmol). b Isolated yield. | ||||
1 | 0.007 | 80 | 100 | 72 |
2 | 0.007 | 90 | 100 | 86 |
3 | 0.007 | 100 | 40 | 90 |
4 | 0.007 | 110 | 10 | 98 |
5 | 0.007 | 120 | 10 | 98 |
6 | 0.005 | 110 | 15 | 94 |
7 | 0.01 | 110 | 10 | 98 |
Various solvents such as dichloromethane, acetonitrile, n-hexane, toluene, ethanol, and water and also solvent-free conditions were examined in this model reaction (Fig. 8). According to the results, more effectiveness was found in the absence of solvent compared to using solvents in the model study (98% yield within 10 min).
Fig. 8 The preparation of dihydroquinazolin-4(1H)-one in the presence of different solvents and under solvent-free conditions. |
We used diverse anilines, aldehydes with isatoic anhydride, when we applied the optimal protocol to assess the efficiency and scope of this reaction. It should be noted that the reaction efficiently continues to provide the correspondent product in outstanding yields. This technique presented a decent tolerance for different substitutions (Table 2). Moreover, the effects of position and the electronic nature of groups on the phenyl rings displayed no robust influence on the synthesis. Moreover, dihydroquinazolinones were achieved in excellent yields within a short time (85–98%).
Entry | R | Amine (ArNH2 or NH4OAC) | Product | Time (min) | Yieldb (%) | M.p. °C | Lit. M.p. oC |
---|---|---|---|---|---|---|---|
a Reaction conditions: UiO-66-NH2-MOF@COF (0.007 g), isatoic anhydride, aldehyde, aryl amine or NH4OAc (1:1:1 molar ratio) under free solvent conditions. b Isolated yield. c New products. | |||||||
1 | H | Ph | 4a | 20 | 91 | 213–215 | 214–216 (ref. 56) |
2 | 4-Me | Ph | 4b | 14 | 85 | 211–213 | 213–214 (ref. 57) |
3 | 4-OMe | Ph | 4c | 15 | 89 | 202–204 | 205–207 (ref. 33) |
4 | 4-Cl | Ph | 4d | 16 | 94 | 220–223 | 222–224 (ref. 33) |
5 | 3-NO2 | Ph | 4e | 12 | 92 | 183–185 | 186–188 (ref. 57) |
6 | 4-NO2 | Ph | 4f | 10 | 98 | 192–194 | 195–197 (ref. 57) |
7 | 4-Me | 4-MeC6H4 | 4g | 25 | 90 | 244–246 | 243–247 (ref. 58) |
8 | 4-OMe | 4-ClC6H4 | 4h | 18 | 87 | 243–245 | 244–247 (ref. 59) |
9 | 4-F | 4-Me | 4i | 17 | 93 | 240–242 | 241–243 (ref. 59) |
10 | 4-Cl | 5-Cl, 2-OHC6H3 | 4j | 10 | 89 | 233–236 | 235–237 (ref. 58) |
11 | 2,6-Cl2 | Ph | 4k | 14 | 93 | 231–232 | 234–236 (ref. 57) |
12 | 4-Br | Ph | 4l | 16 | 96 | 218–220 | 221–223 (ref. 57) |
13 | 4-SMe | 4-BrC6H4 | 4m | 25 | 94 | 246–248 | —c |
14 | 3-NO2 | NH4OAC | 6a | 20 | 91 | 184–186 | 186–188 (ref. 33) |
15 | 2-Cl | NH4OAC | 6b | 15 | 96 | 202–204 | 203–205 (ref. 56) |
16 | 4-OH, 3-OMe | NH4OAC | 6c | 25 | 87 | 223–225 | 226–227 (ref. 33) |
17 | H | NH4OAC | 6d | 20 | 91 | 222–224 | 225–226 (ref. 57) |
18 | 4-OMe | NH4OAC | 6e | 17 | 93 | 187–189 | 192–193 (ref. 57) |
19 | 4-Me | NH4OAC | 6f | 19 | 89 | 230–232 | 233–234 (ref. 57) |
20 | 4-SMe | NH4OAC | 6g | 20 | 87 | 235–237 | —c |
Ultimately, the merits of this method are demonstrated by comparing our catalyst with some of the other reported catalysts. Some representative examples are the reaction of 4-nitrobenzaldehyde, isatoic anhydride, and aniline. As seen from Table 3, our method in this paper presented superior results to most of the methods in the literature.
Entry | Catalyst | Conditions | Time/yield (%) | References |
---|---|---|---|---|
a Based on the reaction between isatoic anhydride, aniline and 4-nitrobenzaldehyde. | ||||
1 | Zn(PFO)2 | EtOH/reflux | 6 h/77–82 | 35 |
2 | P-TSA | EtOH/reflux | 3 h/68–85 | 37 |
3 | Silica sulfuric acid | Solvent-free, 80 °C | 5 h/70–80 | 38 |
4 | Montmorillonite K-10 | EtOH/reflux | 6.5 h/73–92 | 40 |
5 | Ga(OTf)3 | EtOH/70 °C/stir | 35 min/71–91 | 41 |
6 | UiO-66-NH2-MOF@COF | Solvent-free, 110 °C | 10 min/98 | This work |
We proposed a mechanism for synthesizing dihydroquinazolines through the UiO-66-NH2-MOF@COF nanocomposite based on our studies and also according to the previous literature which is presented in Scheme 4.41 The catalyst has both Lewis acidic sites (Zr2+) and basic sites (imine groups of the COF) on its surfaces while abstracting the acidic protons of the reactants and activating the carbonyl groups and double bonds of the substrates and intermediates.60 Mechanistically, the reaction can proceed through the primary activation of the isatoic anhydride. Next, an intermediate I is produced, by attacks of the N-nucleophilic amine on the carbonyl moiety, presenting intermediate IIvia decarboxylation reaction. 2-Amino-N-substituted-amide III is formed via the proton transfer of intermediate II. The proton capture of intermediate II by an intramolecular reaction leads to the creation of intermediate III which undertakes nucleophilic attack on aryl aldehyde for the formation of the imine intermediate IV. In intermediate IV, the catalyst activates the imine moiety associated with intramolecular cyclization by imine to form intermediate Vvia a cyclization reaction. Then, the corresponding products are obtained by a 1,5-proton shift.
Scheme 4 Proposed mechanism pathway for the synthesis of 2,3-dihydroquinazolin-4(1H)-ones using UiO-66-NH2-MOF@COF. |
In addition, the FT-IR spectrum, XRD pattern, and SEM image of the catalyst after six cycles were recorded. As seen from Fig. 10, the intensity of some peaks was reduced but the crystalline structure of the catalyst remained. Comparison of the SEM image of the reused catalyst with that of the fresh catalyst shows more agglomeration of the particles in the recovered catalyst. These facts prove that the efficiency, appearance, and structure of the UiO-66-NH2-MOF@COF catalyst remained intact in the recycled catalyst and there was no considerable deformation.
Fig. 10 SEM images (a), FT-IR spectrum (b), and XRD pattern (c) of the recovered UiO-66-NH2-MOF@COF after 6 runs. |
Footnote |
† Electronic supplementary information (ESI) available. See DOI: https://doi.org/10.1039/d3na00805c |
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