Investigating catalytic pathways: a comparative review of homogeneous and heterogeneous catalysis for 3-aroylimidazo[1,2-a]pyridine synthesis.

3-aroylimidazo[1,2-a]pyridines represent a class of derivatives in the imidazo[1,2-a]pyridine family known for their important biological and pharmaceutical activities. Consequently, various methodologies have been designed to simplify the synthesis of this structure, with an emphasis on the use of cost-effective starting materials and environmentally friendly protocols. All the methods developed in recent years (from 2016 to 2023) rely on homogeneous or heterogeneous catalysts. Therefore, we aim to perform a comparative analysis between these two approaches, elucidating their respective advantages and limitations. The first part of this work focuses on techniques employing homogeneous catalysts, followed by the next section devoted to heterogeneous catalysts. This comprehensive review should be of substantial interest to researchers in the fields of organic and medicinal chemistry, as it provides a valuable resource for their research.

Mesoporous Silica Modified with 2-Phenylimidazo[1,2-a] pyridine-3-carbaldehyde as an Effective Adsorbent for Cu(II) from Aqueous Solutions: A Combined Experimental and Theoretical Study.

In this study, we will present an efficient and selective adsorbent for the removal of Cu(II) ions from aqueous solutions. The silica-based adsorbent is functionalized by 2-phenylimidazo[1,2-a] pyridine-3-carbaldehyde (SiN-imd-py) and the characterization was carried out by applying various techniques including FT-IR, SEM, TGA and elemental analysis. The SiN-imd-py adsorbent shows a good selectivity and high adsorption capacity towards Cu(II) and reached 100 mg/g at pH = 6 and T = 25 °C. This adsorption capacity is important compared to other similar adsorbents which are currently published. The adsorption mechanism, thermodynamics, reusability and the effect of different experimental conditions, such as contact time, pH and temperature, on the adsorption process, were also investigated. In addition, a theoretical study was carried out to understand the adsorption mechanism and the active sites of the adsorbent, as well as the stability of the complex formed and the nature of the bonds.

A Highly Efficient Environmental-Friendly Adsorbent Based on Schiff Base for Removal of Cu(II) from Aqueous Solutions: A Combined Experimental and Theoretical Study.

Removal of heavy metals from drinking water sources and rivers is of strategic health importance and is essential for sustainable ecosystem development, in particular in polluted areas around the globe. In this work, new hybrid inorganic-organic material adsorbents made of ortho- (Si-o-OR) or para-Schiff base silica (Si-p-OR) were synthesized and characterized in depth. These hybrid adsorbents show a high selectivity to Cu(II), even in the presence of competing heavy metals (Zn(II), Cd(II), and Pb(II)), and also demonstrate great reusability after five adsorption-desorption cycles. Maximum sorption capacity for Cu(II) was found for Si-o-OR (79.36 mg g-1) and Si-p-OR (36.20 mg g-1) in no less than 25 min. Energy dispersive X-ray fluorescence and Fourier transform-infrared spectroscopy studies demonstrate that this uptake occurs due to a chelating effect, which allows these adsorbents to trap Cu(II) ions on their surfaces; this result is supported by a theoretical study for Si-o-OR. The new adsorbents were tested against real water samples extracted from two rivers from the Oriental region of Morocco.

Kinetics, thermodynamics, equilibrium, surface modelling, and atomic absorption analysis of selective Cu(ii) removal from aqueous solutions and rivers water using silica-2-(pyridin-2-ylmethoxy)ethan-1-ol hybrid material.

The removal of heavy metals is attracting considerable attention due to their undesirable effects on the environment. In this investigation, a new adsorbent based on silica functionalized with pyridin-2-ylmethanol (SiPy) was successfully synthesized to yield to a hybrid material. FTIR, SEM, TGA, and specific surface area analysis were used to characterize the structure and morphology of the SiPy hybrid material. Various heavy metal ions such as Cu(ii), Zn(ii), Cd(ii), and Pb(ii) were selected to examine the adsorption efficiency of the newly prepared adsorbent, optimized at varying solution pH, contact time, concentration, and temperature. The adsorbent SiPy displayed good adsorption capacity of 90.25, 75.38, 55.23, and 35.12 mg g-1 for Cu(ii), Zn(ii), Cd(ii), and Pb(ii), respectively, at 25 min and pH = 6. The adsorption behaviors of metal ions onto the SiPy adsorbent fitted well with the pseudo-second-order kinetic mode and the isotherm was better described by the Langmuir isotherm. The thermodynamic studies disclose spontaneous and endothermic adsorption process. Furthermore, the SiPy adsorbent retained good selectivity and regeneration properties after five adsorption-desorption cycles of Cu(ii). A computational investigation of the adsorption mechanism indicates that the N-pyridine, O-hydroxyl, and ether O-atoms play a predominant role during the capture of Cu(ii), Zn(ii), Cd(ii), and Pb(ii). This study proposes the SiPy adsorbent as an attractive material for the selective removal of Cu(ii) from real river water and real industrial wastewater.

Crystal structure, Hirshfeld surface analysis and DFT studies of 6-[(E)-2-(thio-phen-2-yl)ethenyl]-4,5-di-hydro-pyridazin-3(2H)-one.

In the title compound, C10H10N2OS, the five atoms of the thio-phene ring are essentially coplanar (r.m.s. deviation = 0.0037 Å) and the pyridazine ring is non-planar. In the crystal, pairs of N-H⋯O hydrogen bonds link the mol-ecules into dimers with an R 2 2(8) ring motif. The dimers are linked by C-H⋯O inter-actions, forming layers parallel to the bc plane. The theoretical geometric parameters are in good agreement with XRD results. The inter-molecular inter-actions were investigated using a Hirshfeld surface analysis and two-dimensional fingerprint plots. The Hirshfeld surface analysis of the title compound suggests that the most significant contributions to the crystal packing are by H⋯H (39.7%), C⋯H/H⋯C (17.3%) and O⋯H/H⋯O (16.8%) contacts.

Crystal structures and Hirshfeld surface analyses of 4-benzyl-6-phenyl-4,5-di-hydro-pyridazin-3(2H)-one and methyl 2-[5-(2,6-di-chloro-benz-yl)-6-oxo-3-phenyl-1,4,5,6-tetra-hydropyridazin-1-yl]acetate.

The asymmetric units of the title compounds both contain one nonplanar mol-ecule. In 4-benzyl-6-phenyl-4,5-di-hydro-pyridazin-3(2H)-one, C17H14N2O, (I), the phenyl and pyridazine rings are twisted with respect to each other, making a dihedral angle of 46.69 (9)°; the phenyl ring of the benzyl group is nearly perpendicular to the plane of the pyridazine ring, the dihedral angle being 78.31 (10)°. In methyl 2-[5-(2,6-di-chloro-benz-yl)-6-oxo-3-phenyl-1,4,5,6-tetra-hydropyridazin-1-yl]acetate, C20H16Cl2N2O3, (II), the phenyl and pyridazine rings are twisted with respect to each other, making a dihedral angle of 21.76 (18)°, whereas the phenyl ring of the di-chloro-benzyl group is inclined to the pyridazine ring by 79.61 (19)°. In the crystal structure of (I), pairs of N-H⋯O hydrogen bonds link the mol-ecules into inversion dimers with an R 2 2(8) ring motif. In the crystal structure of (II), C-H⋯O hydrogen bonds generate dimers with R 1 2(7), R 2 2(16) and R 2 2(18) ring motifs. The Hirshfeld surface analyses of compound (I) suggests that the most significant contributions to the crystal packing are by H⋯H (48.2%), C⋯H/H⋯C (29.9%) and O⋯H/H⋯O (8.9%) contacts. For compound (II), H⋯H (34.4%), C⋯H/H⋯C (21.3%) and O⋯H/H⋯O (16.5%) inter-actions are the most important contributions.

Crystal structure and Hirshfeld surface analysis of (E)-6-(4-hy-droxy-3-meth-oxy-styr-yl)-4,5-di-hydro-pyridazin-3(2H)-one.

In the title com-pound, C13H14N2O3, the dihydropyridazine ring (r.m.s. deviation = 0.166 Å) has a screw-boat conformation. The dihedral angle between its mean plane and the benzene ring is 0.77 (12)°. In the crystal, inter-molecular O-H⋯O hydrogen bonds generate C(5) chains and N-H⋯O hydrogen bonds produce R 2 2(8) motifs. These types of inter-actions lead to the formation of layers parallel to (12). The three-dimensional network is achieved by C-H⋯O inter-actions, including R 2 4(8) motifs. Inter-molecular inter-actions were additionally investigated using Hirshfeld surface analysis and two-dimensional fingerprint plots. The most significant contributions to the crystal packing are by H⋯H (43.3%), H⋯C/C⋯H (19.3%), H⋯O/H⋯O (22.6%), C⋯N/N⋯C (3.0%) and H⋯N/N⋯H (5.8%) contacts. C-H⋯π inter-actions and aromatic π-π stacking inter-actions are not observed.

Crystal structure and Hirshfeld surface analysis of 4-(4-methyl-benz-yl)-6-phenyl-pyridazin-3(2H)-one.

In this paper, we describe the synthesis of a new di-hydro-2H-pyridazin-3-one derivative. The mol-ecule, C18H16N2O, is not planar; the benzene and pyridazine rings are twisted with respect to each other, making a dihedral angle of 11.47 (2)°, and the toluene ring is nearly perpendicular to the pyridazine ring, with a dihedral angle of 89.624 (1)°. The mol-ecular conformation is stabilized by weak intra-molecular C-H⋯N contacts. In the crystal, pairs of N-H⋯O hydrogen bonds link the mol-ecules into inversion dimers with an R 2 2(8) ring motif. The inter-molecular inter-actions were investigated using Hirshfeld surface analysis and two-dimensional (2D) fingerprint plots, revealing that the most important contributions for the crystal packing are from H⋯H (56.6%), H⋯C/C⋯H (22.6%), O⋯H/H⋯O (10.0%) and N⋯C/C⋯N (3.5%) inter-actions.

Crystal structure and Hirshfeld surface analysis of ethyl 2-[5-(3-chloro-benz-yl)-6-oxo-3-phenyl-1,6-di-hydro-pyridazin-1-yl]acetate.

The title pyridazinone derivative, C21H19ClN2O3, is not planar. The unsubstituted phenyl ring and the pyridazine ring are inclined to each other, making a dihedral angle of 17.41 (13)° whereas the Cl-substituted phenyl ring is nearly orthogonal to the pyridazine ring [88.19 (13)°]. In the crystal, C-H⋯O hydrogen bonds generate dimers with R 2 2(10) and R 2 2(24) ring motifs which are linked by C-H⋯O inter-actions, forming chains extending parallel to the c-axis direction. The inter-molecular inter-actions were investigated using Hirshfeld surface analysis and two-dimensional fingerprint plots, revealing that the most significant contributions to the crystal packing are from H⋯H (44.5%), C⋯H/H⋯C (18.5%), H⋯O/H⋯O (15.6%), Cl⋯H/H⋯Cl (10.6%) and C⋯C (2.8%) contacts.

Crystal structure and the DFT and MEP study of 4-benzyl-2-[2-(4-fluoro-phen-yl)-2-oxoeth-yl]-6-phenyl-pyridazin-3(2H)-one.

The title pyridazin-3(2H)-one derivative, C25H19FN2O2, crystallizes with two independent mol-ecules (A and B) in the asymmetric unit. In mol-ecule A, the 4-fluoro-phenyl ring, the benzyl ring and the phenyl ring are inclined to the central pyridazine ring by 86.54 (11), 3.70 (9) and 84.857 (13)°, respectively. In mol-ecule B, the corresponding dihedral angles are 86.80 (9), 10.47 (8) and 82.01 (10)°, respectively. In the crystal, the A mol-ecules are linked by pairs of C-H⋯F hydrogen bonds, forming inversion dimers with an R 2 2(28) ring motif. The dimers are linked by C-H⋯O hydrogen bonds and a C-H⋯π inter-action, forming columns stacking along the a-axis direction. The B mol-ecules are linked to each other in a similar manner and form columns separating the columns of A mol-ecules.

Crystal structure and Hirshfeld surface analysis of 4-(2,6-di-chloro-benz-yl)-6-phenyl-pyridazin-3(2H)-one.

The asymmetric unit of the title compound, C17H12Cl2N2O, contains one independent mol-ecule. The mol-ecule is not planar, the phenyl and pyridazine rings are twisted with respect to each other, making a dihedral angle of 29.96 (2)° and the di-chloro-phenyl ring is nearly perpendicular to the pyridazine ring, with a dihedral angle of 82.38 (11)°. In the crystal, pairs of N-H⋯O hydrogen bonds link the mol-ecules to form inversion dimers with an R 2 2(8) ring motif. The dimers are linked by C-H⋯O inter-actions, forming layers parallel to the bc plane. The inter-molecular inter-actions were investigated using Hirshfeld surface analysis and two-dimensional fingerprint plots, and the mol-ecular electrostatic potential surface was also analysed. The Hirshfeld surface analysis of the title compound suggests that the most significant contributions to the crystal packing are by H⋯H (31.4%), Cl⋯H/H⋯Cl (19.9%) and C⋯H/H⋯C (19%) contacts.

Crystal structure of (E)-4-[N-(7-methyl-2-phenyl-imidazo[1,2-a]pyridin-3-yl)carboximido-yl]phenol.

The mol-ecule of the title compound, C21H17N3O, is built up from fused five- and six-membered rings connected to a methyl group, a phenyl ring and an (imino-meth-yl)phenol group. The fused ring system is almost planar (r.m.s. deviation = 0.031 Å) and forms dihedral angles of 64.97 (7) and 18.52 (6)° with the phenyl ring and the (imino-meth-yl)phenol group, respectively. In the crystal, centrosymmetric mol-ecules are linked by pairs of C-H⋯π inter-actions into dimeric units, which are further connected by O-H⋯N hydrogen bonds to form layers parallel to (101).

Crystal structure of (5-methyl-imidazo[1,2-a]pyridin-2-yl)methanol.

In the title compound, C9H10N2O, the imidazo[1,2-a]pyridine moiety is approximately planar (r.m.s. deviation = 0.024 Å). The methanol group is nearly perpendicular to its mean plane as indicated by the C-C-C-O and N-C-C-O torsion angles of 80.04 (16) and -96.30 (17)°, respectively. In the crystal, mol-ecules are linked by O-H⋯N hydrogen bonds, forming inversion dimers with an R (2) 2(10) ring motif. The dimers are liked via C-H⋯O hydrogen bonds, enclosing R (2) 2(10) ring motifs and forming ribbons along [201]. The ribbons are linked via a number of π-π inter-actions [centroid-centroid distances vary from 3.4819 (8) to 3.7212 (8) Å], forming a three-dimensional structure.