Lack of specificity and subsequent therapeutic effectiveness of antimicrobial and antitumoral drugs is a common difficulty in therapy. The aim of this study is to investigate, both by experimental ...and computational methods, the antitumoral and antimicrobial properties of a series of synthesized imidazole-pyridine derivatives. Interaction with three targets was discussed: Dickerson-Drew dodecamer (PDB id 2ADU), G-quadruplex DNA string (PDB id 2F8U) and DNA strain in complex with dioxygenase (PDB id 3S5A). Docking energies were computed and represented graphically. On them, a QSAR model was developed in order to further investigate the structure-activity relationship. Results showed that synthesized compounds have antitumoral and antimicrobial properties. Computational results agreed with the experimental data.
•Synthesis of two Isoxazoles from commercially available acetophenones is reported•Target compounds are a tetrazole–acid and an imidazole–acid as potential ligands•Structural characterization of ...intermediates and target compounds has been provided•X-ray structure for the isoxazole-containing imidazole–acid has been determined•Detailed molecular modeling of the imidazole–acid has been performed
Two novel di-topic hybrid ligands, useful for the generation of coordination polymers, have been synthesized. These ligands feature an isoxazole ring in their central unit, and have as coordinating moieties a carboxylate group at one end of the central unit, and either a tetrazole or an imidazole at the other end. The structure of the hydrochloride monohydrate of the imidazole–acid has been established by single crystal X-ray diffraction. Molecular structure of the imidazole–acid was also investigated theoretically. The optimized molecular geometry was found to be in good agreement with the structure determined by single-crystal X-ray diffraction (RMSD = 0.2046 Å). The experimental maximum electronic absorption band observed at 294 nm in DMSO was reasonably close to the theoretical wavenumber of 296 nm computed by TD-DFT method. The energy gap (HOMO-LUMO), atomic charges distribution, mapped electrostatic potential; dipole moment, reactive descriptors, and calculated vibrational frequencies for the ligand were determined and discussed.
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A series of isoreticular lanthanide–organic frameworks derived from a lengthy dicarboxylate ligand with a terphenyl core have been synthesized and characterized. Evaluation of their luminescence ...showed that the Tb3+-MOF has an expected emission quantum yield of 98%.
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•Solvothermal synthesis of lanthanide–organic frameworks is reported.•Single crystal X-ray structures were established for six coordination polymers.•These isoreticular networks include nitrate, water and DMF in their structure.•Luminescent properties of these MOFs have been investigated.•Tb(III)-based MOF has an expected emission quantum yield of 98%.
A series of 3D metal–organic frameworks derived from 2′,3′,5′,6′-tetramethyl-1,1′:4′,1′′-terphenyl-4,4′′-dicarboxylic acid (H2L) as organic linker and various lanthanides have been prepared. The resulting coordination polymers Ln3L4(NO3)(DMF)x(H2O)n (where x = 2 or 3) were characterized by elemental analysis, thermogravimetric investigations, IR and TG-FTIR spectroscopy, as well as powder X-ray diffraction measurements. The crystal structure for six of these isostructural networks based on La(III), Ce(III), Nd(III), Sm(III), Tb(III) and Dy(III) was established using single crystal X-ray crystallography. As an example, the asymmetric part of La3L4(NO3)(DMF)3(H2O)n consists of two deprotonated ligand molecules L2- and two La(III) ions, one of them occupying a general position with full site occupancy, while the other one has a fractional occupancy of 0.5. Investigation of the luminescence of these coordination polymers showed that compounds containing La3+, Nd3+ and Gd3+ possess only the emission associated with the anion of the organic ligand (L2-), polymers containing Eu3+ and Tb3+ show pure metal-centered radiation, while networks containing Dy3+ and Sm3+ display dual metal- and ligand-centered luminescence. The organic linker acts as a good antenna for Tb3+, Eu3+, Dy3+ and Sm3+ ions.
Examination of the potential of the title ligand for the generation of coordination compounds with transition metal ions led to the isolation of novel Cd(II)-based networks and Cu(II)-based ...complexes. Cd(II)-containing networks derived from this ligand that also incorporate co-ligands (4,4′-bipyridine or 4,4′-azopyridine) in their structure have been described for the first time.
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The straightforward and facile synthetic approaches towards four coordination polymers, {CdL(H2O)·0.5H2O}n, {Cd2L2(H2O)2(4,4′-bipy)·4H2O}n, {Cd2L2(H2O)2(4,4′-azpy)·3H2O}n and {CoL(H2O)3·2.5H2O}n (4,4′-bipy = 4,4′-bipyridine; 4,4′-azpy = 4,4′-azopyridine), based on the polydentate ligand 1-(4-carboxyphenyl)-5-methyl-1H-1,2,3-triazole-4-carboxylic acid (LH2) and Cd(II) and Co(II) ions are reported. In addition, two mononuclear complexes, Cu(HL)2(DMA) and Cu(HL)2(H2O)2, derived from the same ligand and the Cu(II) ion have been prepared. The coordination compounds have been characterized by infrared spectroscopy, thermogravimetry, powder X-ray diffraction and elemental analysis. Single crystal X-ray structures for each of these coordination compounds have been established. The specific surface of the 3D Cd(II)- and Co(II)-derived coordination polymers, determined through nitrogen adsorption, is negligible (SBET < 25 m2/g).
Four novel ditopic ligands that have a pyrazole ring in their central unit and are useful for the generation of coordination polymers have been synthesized. Two of these ditopic ligands present two ...carboxylate functions as coordinating groups, while the other two are hybrid ligands having only one carboxylate function and either tetrazolate or imidazole as the remaining coordination site. The ligands have been obtained through a multi-step reaction sequence that begins with the Claisen condensation of either 4-acetylbenzonitrile or 4-(1
H
-imidazol-1-yl)acetophenone with diethyl oxalate and has the Knorr pyrazole ring closure as its key step. Subsequently, the tetrazolate in one of the ligands is constructed through a 3 + 2 cycloaddition of azide anion to the cyano group, while hydrolysis of the ester and the cyano substituents generates the carboxylate function(s). The structure of the intermediates and of the target ligands has been investigated by solution NMR, special attention being given to keto–enol and pyrazole tautomerism when present. The structure of two ligands and a key intermediate has also been established by single-crystal X-ray diffraction.
Coordination polymers of 2′,3′,5′,6′-tetramethyl-1,1′:4′,1′′-terphenyl-4,4′′-dicarboxylic acid with Cu(II), Co(II) and Cd(II) have been synthesized and characterized by IR spectroscopy, single ...crystal X-ray diffraction, thermogravimetric analysis and nitrogen sorption studies.
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Three new 3D-metal–organic frameworks based on 2′,3′,5′,6′-tetramethyl-1,1′:4′,1′′-terphenyl-4,4′′-dicarboxylic acid (H2L) and Co, Cu, and Cd nodes have been synthesized. The complexes were characterized by elemental, thermogravimetric analysis, IR spectroscopy, single crystal, powder X-ray diffraction and gas sorption experiments. The crystal structure of Cu2L2(H2O)2n (1) corresponds to a two-dimensional coordination polymer, in which the metal nodes are two crystallographically equivalent Cu(II) atoms linked by four μ2-O,O′ carboxylate ligands in a centrosymmetric {Cu2O10} paddle-wheel building block. The structure of compound CoL(dmso)n (2) has a 3D metal–organic coordination lattice, in which the metal centers are connected by the linear organic ligand to generate a dense three-dimensional coordination polymer. Also, a three-dimensional coordination network was identified in the case of compound Cd2L2(dmf)n (3), whose structure is very similar to that of compound 2. In compound 3, the carboxylate groups of the linear L2− spacers behave as μ2-κ3O, O′:O tridentate bridging ligands. The compounds have a high thermal stability. Polymers 3 and 1 have moderate porosity (specific surface areas of approximately 900 m2/g and 600 m2/g, respectively), while polymer 2 has a dense structure.
Two synthetic approaches towards 4′-(2H-tetrazol-5-yl)-1,1′-biphenyl-4-carboxylic acid, a valuable organic ligand for the preparation of metal-organic frameworks, are reported. The first reaction ...sequence leading to the target compound comprises the iodination of 1,1′-biphenyl-4-carboxylic acid, formation of the methyl ester of 4′-iodo-1,1′-biphenyl-4-carboxylic acid, nucleophilic substitution of iodine with cyano, ring closure of tetrazole, and hydrolysis of the ester function. The second synthetic pathway starts from 4-bromobenzonitrile, which is converted through Suzuki coupling with 4-carboxyphenylboronic acid into 4′-cyano-1,1′-biphenyl-4-carboxylic acid, which in turn leads to the desired compound after ring closure of tetrazole. All of the synthesized compounds have been fully characterized by IR and 1H- and 13C-NMR spectroscopy. Single crystal X-ray structures are reported for the target compound and for methyl esters of 4′-iodo-1,1′-biphenyl-4-carboxylic acid and 4′-cyano-1,1′-biphenyl-4-carboxylic acid. The target compound and the intermediates showed no antimicrobial activity against Escherichia coli, Staphylococcus aureus and Candida albicans.
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•Synthesis of the title compound has been performed through two distinct approaches.•Structural characterization has been performed using IR and NMR spectroscopy.•Single crystal X-ray structures have been determined for two intermediates.•Single crystal X-ray structure has been established for the title compound.•Preliminary antimicrobial activity of the compounds has been evaluated.
