Co (II) and Cd (II) complexes with imidazole‐2‐carboxaldehyde groups: spectroscopic, antibacterial, Hirshfeld surfaces analyses, and TD/DFT calculations

et al. 2021

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The quinazoline-type ligand 2-(3-ethoxy-2-hydroxyphenyl)-4-methyl-1,-2-dihydroquinazolin 3-oxide (HL 1 , H is the deprotonatable hydrogen) was synthesized. Two mono-and dinuclear Cu (II) complexes, [Cu(L 2 ) 2 ]Á2CH 3 OH (1),amino}phenyl)ethanone oxime), were obtained via complexation of HL 1 with Cu (II) acetate monohydrate or Cu (II) nitrate trihydrate in methanol. HL 1 and both complexes were characterized by elemental analyses and spectroscopic methods. The structures of complexes were confirmed by single-crystal X-ray crystallography and the ratio of ligand to metal in 1 was 2:1 whereas 2 was 1:1. In the crystal structures, hexa-coordinated Cu (II) complex 1 was assembled into an infinite 1-D, 2-D network and 3-D supramolecular framework. Complex 2 included four deprotonated (L 2 ) À units, four coordinated Cu (II) and two coordinated nitrate anions, forming an infinite 2-D layer and interesting butterfly-shaped 3-D supramolecular skeleton. Specifically, the Cu1 and Cu4 centers were four-coordinated, while the Cu2 and Cu3 centers were penta-coordinated in 2. Furthermore, electrochemical properties and antibacterial activities of both complexes were also investigated. In addition, the electron paramagnetic resonance (EPR) spectra of 1 and 2 were also studied. The optimal geometries, HOMO-LUMO energies and molecular electrostatic potential diagrams of two complexes were calculated using density functional theory (DFT)/B3LYP, and specific electronic transitions in the UVvis spectra of 1 and 2 were recorded by time-dependent DFT (TD-DFT) calculations. Additionally, the noncovalent interactions between both complexes were also confirmed by Hirshfeld surfaces.

Section: Resultsmentioning

confidence: 99%

Two mono‐ and dinuclear Cu (II) complexes derived from 3‐ethoxy salicylaldehyde: X‐ray structures, spectroscopic, electrochemical, antibacterial activities, Hirshfeld surfaces analyses, and time‐dependent density functional theory studies

et al. 2021

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“…The energy gap (ΔE = E LUMO À E HOMO ) was intended to be the energy difference of frontier molecular orbitals and was very significant in the photochemical reaction, absorption, and luminescence property of the compound. [58,59] The computed energy gaps of 1 for α-spin and β-spin were 0.714 and 0.669 eV, as well as the ΔE of 2 was 2.789 eV. The larger energy gap manifested excellent chemical stability.…”

Section: Theoretical Investigationsmentioning

confidence: 97%

Antimicrobial activities of two 1‐D, 2‐D, and 3‐D mononuclear Mn (II) and dinuclear Bi (III) complexes: X‐ray structures, spectroscopic, electrostatic potential, Hirshfeld surface analysis, and time‐dependent/density functional theory studies

Zhang

et al. 2022

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Two mononuclear and dinuclear octahedral complexes, [Mn(L1)2Cl2] (1) and [Bi2(L2)2Cl8] (2) (L1 = 2‐(2‐pyridyl)‐4‐methyl‐1,2‐dihydroquinazoline‐N3‐oxide, L2 = 2‐(3‐pyridyl)‐4‐methyl‐1,2‐dihydroquinazoline‐N3‐oxide) were prepared by natural volatilization method. The ligands and both complexes were compared with spectroscopic methods, as well as characterized by elemental analysis. The photoluminescence behaviors of both complexes in different solvents were also investigated. The coordination possibility of ligands toward Mn (II)/Bi (III) was verified using X‐ray crystallography, and it revealed that the ratio of ligand to metal was 2:1 in 1, whereas 1:1 in 2. The adjacent molecules of six‐coordinated complex 1 constituted an infinite 1‐D chain, 2‐D network, and ladder‐like 3‐D supramolecular frameworks. Most strikingly, hexa‐coordinated complex 2 with dinuclear structure formed an infinite 1‐D chain, 2‐D layered and meter‐shaped 3‐D supramolecular skeleton. Density functional theory (DFT) calculation was used to optimize the geometry of complexes, compute the electrostatic potential diagrams, and evaluate the HOMO‐LUMO energy gap. The electronic transition simulated through time‐dependent (TD)‐DFT level of calculation rationalized the experimental data. The antibacterial properties of all compounds were evaluated against Gram‐positive and Gram‐negative bacterial strains. In addition, the Hirshfeld surface was utilized to quantify some hydrogen bonding interactions and their contributions.

“…The 2-(2-Imidazolyl)-4-methyl-1,2-dihydroquinazoline-N 3 -oxide (L) was synthesized through the similar method of literature reported previously. [21]…”

Section: Synthesis and Structural Characterization Of Lmentioning

confidence: 99%

Novel zinc (II) and nickel (II) complexes of a quinazoline‐based ligand with an imidazole ring: Synthesis, spectroscopic property, antibacterial activities, time‐dependent density functional theory calculations and Hirshfeld surface analysis

et al. 2022

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Two complexes [Zn(L) 2 (CH 3 OH) 2 ](NO 3 ) 2 (1) and [Ni(L) 3 ]Á(NO 3 ) 2 (2) (L = 2-[2-imidazolyl]-4-methyl-1,2-dihydroquinazoline-N 3 -oxide) were obtained successfully by means of slow evaporation solution technique (SEST)and characterized using elemental analysis, FT-IR, UV-vis, and fluorescence spectroscopic. X-ray diffraction revealed that the metal in complex 1 is chelated by two L ligands and two lattice methanol molecules, whereas in 2 by three L ligands, counterbalanced by nitrate ions. The crystal structures of both showed infinite 1-D, 2-D, and 3-D supramolecular architecture due to intermolecular interactions. Most strikingly, Zn (II) complex showed different fluorescence properties in diverse solvents. The antimicrobial activities of all compounds were compared and showed perceptible efficiency against Gramnegative and Gram-positive bacteria. Electrostatic potential (ESP) calculation was used to predict the nucleophilic and electrophilic attack sites. Density functional theory (DFT) calculation results showed good agreement with experimental data, as well as the frontier molecular orbital energy gaps were detected by time-dependent (TD)-DFT method with HOMO-LUMO calculations. Additionally, the non-covalent interactions of both complexes were further quantified and explored with the help of Hirshfeld surface analysis.