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Two novel complexes [Zn(L)2·(NO3)2] (1) and [Ni(L)2·2H2O]·2CH3OH·(NO3)2 (2) (L = 2‐(2‐thiazolyl)‐4‐methyl‐1,2‐dihydroquinazoline‐N3‐oxide) were synthesized successfully and characterized by elemental analysis, as well as various spectroscopic techniques. Specifically, the photoluminescence behavior of complex 1 was explored in different solvents. The structural characterization of both complexes has been determined single‐crystal X‐ray diffraction. It revealed that the metals in 1 and 2 are chelated by two L ligands in centro‐symmetrically fashion and the complexes are counterbalanced by nitrate ions which act as coordinating species in 1, while two water molecules complete the Ni coordination sphere in 2. In the crystal structures, the adjacent molecules of complex 1 disclosed a ladder‐like 2‐D network and 3‐D supramolecular self‐assembly. Simultaneously, an infinite 1‐D chain, 2‐D layered skeleton, and even meter‐shaped 3‐D network of 2 was governed by molecular interactions (H–bonds, C–H⋯π). Most strikingly, the research of antibacterial activity proved that two complexes had good activity against two standard bacteria strains. To ascertain deeply the optimum geometric configurations and detect the frontier molecular orbital energy gaps, density functional theory (DFT) calculations were also investigated. Additionally, analyses of Hirshfeld surfaces (HS) and electrostatic potential (ESP) were also performed to quantify the presence of diverse noncovalent interactions. [ABSTRACT FROM AUTHOR]

Two mono‐ and dinuclear Bi(III) complexes, [Bi(L)2(NO3)2]·NO3 (1) and [Bi2(L)2Cl8] (2) (L = (2‐(2‐pyridyl)‐4‐methyl‐1,2‐dihydroquinazoline‐N3‐oxide), were obtained via complexation of L with Bi(III) nitrate pentahydrate and Bi(III) chloride. L and both complexes were characterized by elemental analyses and spectroscopic methods including FT‐IR, UV–Vis, and fluorescence spectroscopy. Specifically, it clearly manifested that both complexes had good fluorescence emission and showed different fluorescence behaviors in diverse solvents. Both Bi(III) complexes were further determined by X‐ray crystallography, and it was found that the ratio of ligand to metal was 2:1 in 1, whereas 2 was 1:1. Their coordination geometric configurations were significantly different, such as octa‐coordinated complex 1 formed an infinite 1‐D chain‐like, funnel‐shaped 2‐D network, and ladder‐like 3‐D supramolecular framework, whereas hexa‐coordinated complex 2 with a binuclear structure exhibited two slightly distorted octahedral geometric structures; meanwhile, symmetric units came into being an infinite 2‐D layer even and meter‐shaped 3‐D supramolecular skeleton. The optimal geometries, frontier molecular orbital energies, and molecular electrostatic potential diagrams of both complexes were calculated using DFT/B3LYP. The electronic distribution of HOMO‐LUMO rationalized the results of UV–Vis spectra with the help of TD‐DFT calculations. Furthermore, all samples demonstrated excellent antibacterial activities against Escherichia coli and Staphylococcus aureus. In addition, non‐covalent interactions of complexes and their contributions were quantified with Hirshfeld surfaces using CrystalExplorer17 program. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Two complexes [Zn(L)2(CH3OH)2](NO3)2 (1) and [Ni(L)3]·(NO3)2 (2) (L = 2‐[2‐imidazolyl]‐4‐methyl‐1,2‐dihydroquinazoline‐N3‐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 Gram‐negative 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. [ABSTRACT FROM AUTHOR]

The quinazoline‐type ligand 2‐(3‐ethoxy‐2‐hydroxyphenyl)‐4‐methyl‐1,2‐dihydroquinazolin 3‐oxide (HL1, H is the deprotonatable hydrogen) was synthesized. Two mono‐ and dinuclear Cu (II) complexes, [Cu(L2)2]·2CH3OH (1), and [Cu4(L2)4(NO3)2] (2) (HL2 = 1‐(2‐{[(E)‐(3‐ethoxy‐2‐hydroxybenzylidene]amino}phenyl)ethanone oxime), were obtained via complexation of HL1 with Cu (II) acetate monohydrate or Cu (II) nitrate trihydrate in methanol. HL1 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 (L2)− 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 UV–vis 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. [ABSTRACT FROM AUTHOR]

Two complexes [Cd(L)2(NO3)2] (1) and [Ni(L)2(OH)2][Ni(L)2(CH3OH)2](NO3)2·CH3OH (2) (L = 2‐[2‐pyridyl]‐4‐methyl‐1,2‐dihydroquinazolin 3‐oxide) were gained via complexation an amount of the new ligand L with different nitrate salts. The obtained complexes were characterized by elemental analysis, spectroscopy, and X‐ray crystallographic. In the crystal structure, centrosymmetric 1 adopted slightly distorted octahedral geometry. On the other hand, the independent unit of 2 contained two half Ni (II) complex located on a center of symmetry, differing for the axial ligand, two uncoordinated nitrate ions, and one lattice methanol molecule. Both the crystal structures formed a 3‐D supramolecular architecture through different interactions (H‐bonds, π···π, etc). X‐ray crystallography revealed that complexes 1 and 2 had 2:1 ligand‐to‐metal ratios. Most strikingly, 1 performed different fluorescence behaviors in diverse solvents, whereas 2 exhibited fluorescence quenching. When 1 was dissolution in N,N‐dimethylformamide (DMF) solvent system, it has better fluorescence properties. The geometry optimization and HOMOs and LUMOs energies of both complexes were calculated by density functional theory (DFT) methods, and the nucleophilic and electrophilic attack sites were confirmed with electrostatic potential (ESP) calculations. Preliminary investigation of antimicrobial activities of all compounds against Gram‐negative bacteria (Escherichia coli) and Gram‐positive bacteria (Bacillus subtilis) was reported. Additionally, CrystalExplorer program was used to quantify the noncovalent interactions in complexes 1 and 2 through Hirshfeld surface analysis. [ABSTRACT FROM AUTHOR]

Two complexes [Co(L)2·2CH3OH]2·(NO3)4 (1) and [Cd(L)2(NO3)2] (2) (L = 2‐(2‐imidazolyl)‐4‐methyl‐1,2‐dihydroquinazoline‐3‐oxide) were synthesized by natural evaporation of Co (II)/Cd (II) nitrate with a new heterocyclic ligand. The metal complexes are characterized by elemental analysis, spectroscopy, and X‐ray crystallographic. In the crystal structures, Co (II) complex 1 was in a six‐coordinated coordination environment and constituted an infinite 1‐D chain, 2‐D network, Meter‐shaped 3‐D supramolecular framework, while Cd (II) complex 2 assembled into an infinite 1‐D, wave‐like 2‐D, and dragonfly‐shaped 3‐D skeleton. Specifically, nitrate ions were present as a dissociated group in complex 1, whereas complex 2 was involved in the coordination. Moreover, Cd (II) complex exhibited different fluorescence behaviors in diverse solvents. Remarkably, all the compounds have shown perceptible antibacterial activity against Gram‐positive and Gram‐negative bacteria. Furthermore, the electrostatic potential (ESP) calculations were utilized to analyze electrophilic and nucleophilic attack sites on the molecule, which verified the existence of hydrogen bonds in the optimized crystal structure. In addition, the structural features of metal complexes have been remarkably rationalized, and the overall trends obtained in the experimental values have been resoundingly remade by TD/DFT calculations. The detailed Hirshfeld surface analysis and fingerprint plots yielded a comparative picture of the mode of non‐covalent interactions. [ABSTRACT FROM AUTHOR]

• Two 1-D, 2-D and 3-D supramolecular Cu(II) and Ni(II) complexes based on the quinazoline-type ligand L containing pyrazole ring were structural characterized. • The activity data showed the metal complexes to be more antibacterial than the quinazoline-type ligand L. • The experimental investigations match with those obtained from TD-DFT calculations. • ESP calculation results confirmed the charge distribution in the molecule and Hirshfeld surface analyses of both complexes were also discussed. The ligand 2-(3-pyrazolyl)-4-methyl-1,2-dihydroquinazoline-N3-oxide (L) was synthesized, and two transition metal complexes, namely [Cu(L) 2 ]·(NO 3) 2 (1) and [Ni(L) 3 ]·(NO 3) 2 ·3CH 3 OH (2) were prepared through complexation reaction between L and the corresponding metal salt. L and both complexes were characterized by elemental analysis, as well as compared with spectrographic technique for example FT-IR and UV–Vis spectroscopy. X-ray single-crystal diffraction demonstrated that 1 was tetra-coordinated square planar whereas 2 was hexa-coordinated slightly distorted octahedral geometry. Meanwhile, the metal-ligand ratios were 2:1 in 1 whereas 3:1 in 2. Through the superposition of hydrogen bonds and other weak interactions, both complexes formed 1-D chain-like, 2-D layered, and 3-D supramolecular structures. Theoretical investigations explained the optimized geometries of complexes and the electrostatic potential distribution in molecules, and also analyzed the electron transition types of L and both complexes in combination with UV–vis spectroscopy, which provided theoretical support for the experimental conclusions. Electrostatic potential (ESP) was computed for both complexes to predict the reaction positions of electrophilic and nucleophilic assaults. Hirshfeld Surface Analysis quantified interactions in molecules and analyzed the contribution of various weak interactions to stabilize the structure of complexes. Especially, antibacterial experiments displayed compounds had certain antibacterial activities against both Gram-positive and Gram-negative bacterial strains. The ligand 2-(3-pyrazolyl)-4-methyl-1,2-dihydroquinazoline-N3-oxide (L) was synthesized, and two metal complexes, namely [Cu(L) 2 ]·(NO 3) 2 (1) and [Ni(L) 3 ]·(NO 3) 2 ·3CH 3 OH (2) were prepared through complexation reaction between L and the corresponding metal salt. Both complexes were characterized by X-ray crystallography, spectroscopic methods such as FT-IR and UV–Vis spectroscopy, and electrochemical property, as well as Hirshfeld surface analysis and DFT studies. The antimicrobial activities of all compounds were also compared. [Display omitted] [ABSTRACT FROM AUTHOR]

Two two-dimensional supramolecular copper(II) and cobalt(III) complexes, Cu(L1)2 ( 1; HL1 = 2-hydroxy-3-methoxybenzaldehyde oxime) and [Co(L2)2]2⋅2CH3COOCH2CH3 ( 2; HL2 = 1-(2-{[( E)-3-methoxy-2-hydroxybenzylidene]amino}phenyl)ethanone oxime), have been synthesized via complexation of Cu(II) nitrate trihydrate and Co(II) acetate tetrahydrate with HL. A plausible reaction mechanism for the formation of HL1 is proposed. HL was synthesized and characterized using infrared, 1H NMR and 13C NMR spectra, as well as elemental analysis. Complexes 1 and 2 were investigated using single-crystal X-ray diffraction and have a 2:1 ligand-to-metal ratio. Different geometric features of both complexes are observed. In their crystal structures, 1 and 2 form infinite two-dimensional structures and 2 forms a three-dimensional supramolecular framework. Electron paramagnetic resonance spectra of 1 and 2 were also investigated. Moreover, thermal and electrochemical properties and antimicrobial activity of 2 were also studied. In addition, the calculated HOMO and LUMO energies show the character of complex 1. [ABSTRACT FROM AUTHOR]

Two mono- and dinuclear Ni(II) complexes, [Ni( L 3 ) 2 ]·2H 2 O ( 1 ) ( HL 3 = 1-(2-{[( E )-3-methoxy-2-hydroxybenzylidene]amino}phenyl)ethanone oxime) and [Ni 2 ( L 4 ) 2 (CH 3 COO) 2 ] ( 2 ) ( HL 4 = 1-(2-{[( E )-2-hydroxybenzylidene]amino}phenyl)ethanone oxime), have been synthesized via complexation of Ni(II) acetate tetrahydrate with HL 1 and HL 2 ( HL 1 = 2-(2-hydroxy-3-methoxyphenyl)-4-methyl-1,2-dihydroquinazoline 3-oxide, HL 2 = 2-(2-hydroxyphenyl)-4-methyl-1,2-dihydroquinazoline 3-oxide) originally. HL 1 , HL 2 , and two Ni(II) complexes were characterized by IR, UV–Vis, and fluorescence spectroscopy, as well as by elemental analysis, respectively. The spectroscopic data of two Ni(II) complexes were compared with the ligands HL 1 and HL 2 . The differently geometric features of the obtained complexes 1 and 2 are observed by X-ray crystallography. In the crystal structure, complexes 1 and 2 form an infinite 1-D chain and 2 into 2-D supramolecular frameworks. The electrochemical properties of 1 and 2 were also investigated by cyclic voltammetry. Moreover, thermal property of 1 was also studied. In addition, the antimicrobial activity of HL 1 , HL 2 , and complexes 1 and 2 were also investigated. [ABSTRACT FROM AUTHOR]

• Two 2-D and 3-D supramolecular Ni(II) and Co(III) complexes based on 3-ethoxy salicylaldehyde were structural characterized. • X-ray crystallography revealed that the valence of cobalt ion is trivalent, EPR and cyclic voltammetry experiment also proved the result. • The experimental investigations match with those obtained from TD-DFT calculations. • ESP calculation results confirmed the charge distribution in the molecule and Hirshfeld surface analyses of complexes 1 and 2 were also discussed. The ligand 2-(3-ethoxy-2-hydroxyphenyl)-4-methyl-1,2-dihydroquinazolin 3-oxide (HL1 , H is the deprotonatable hydrogen) has been synthesized, and two metal complexes, namely [Ni(L2) 2 ]·2CH 3 OH (1) and [Co(L2) 2 ]·NO 3 ·H 2 O (2) (where HL2 =1-(2-{[(E)-(3- ethoxy -2- hydroxybenzylidene ]amino} phenyl)ethanone oxime) were obtained via complexation reaction between HL1 and nickel(II) acetate tetrahydrate or cobalt(II) nitrate hexahydrate. HL1 and both complexes were characterized by elemental analysis, as well as compared by spectroscopic methods such as FT-IR, UV–Vis and fluorescence spectroscopy. X-ray crystallography revealed that both complexes have distorted octahedral geometries but with a different configuration of the two tridentate (L2)– ligands around the metal centers. Complex 1 contained two lattice methanol molecules whereas 2 were counterbalanced by a nitrate anion beside an uncoordinated water molecule. The crystal structures show a 2-D and 3-D supramolecular architecture due to intermolecular interaction. Electrochemical properties of both complexes were tested by cyclic voltammetry and Electron paramagnetic resonance (EPR) spectroscopy of 2 was also investigated. Fascinatingly, antibacterial efficiencies of all compounds were compared. Furthermore, molecular electrostatic potential (ESP) was computed for both complexes to predict the reaction sites of electrophilic and nucleophilic attacks. Density Functional Theory (DFT) calculations were done to ascertain the optimum geometric configurations. The non-covalent interaction was determined using the Hirshfeld program. The quinazoline-type ligand HL1 , used for the synthesis of two discrete metal complexes, [Ni(L2) 2 ]·2CH 3 OH (1) and [Co(L2) 2 ]·NO 3 ·H 2 O (2), was observed to be modified upon complexation with HL2. Both complexes were characterized by X-ray crystallography, spectroscopic methods such as FT-IR, UV–Vis and fluorescence spectroscopy, and electrochemical properties, as well as Hirshfeld surface analysis and DFT studies. The antimicrobial activities of all compounds were also compared. [Display omitted] [ABSTRACT FROM AUTHOR]

• Packing dimension of supramolecular complexes with N -heterocycle ligand were characterized by X-ray crystallography. • The antibacterial activities demonstrated that the metal complexes were the best among all the compounds and 2 was superior to 1. • The experimental investigation was matched with those obtained from TD-DFT calculations. • ESP calculation results manifested the charge distribution and Hirshfeld surface analyses were also further enhanced. Two 1-D, 2-D, 3-D supramolecular complexes, namely [Ni(L1) 2 (CH 3 OH) 2 ](NO 3) 2 (1) and [Cd(L2) 2 (NO 3) 2 ] (2) with N -heterocycle ligands (L1 = 2-(4-imidazolyl)-4-methyl-1,2-dihydroquinazoline-N3-oxide, L2 = 2-(2-thiazolyl)-4-methyl-1,2-dihydroquinazoline- N 3-oxide), were synthesized by corresponding nitrate and characterized by elemental analysis and spectroscopic methods. X-ray diffraction displayed that both complexes were hexa-coordination geometries and had 2:1 ligand-to-metal ratios. Ni(II) in 1 was coordinated with two L1 and two lattice methanol molecules, counterbalanced by nitrate ions, whereas Cd(II) in 2 by two L2 and nitrate ions. In the crystal structures, 1 based on an infinite 1-D chains to form 2-D wavy-like and 3-D supramolecular self-assembly. Similarly, 2 further developed 2-D and 3-D network structure by several interactions. The electrochemical behavior of 1 in DMF revealed the electronic effects on redox potential of the groups. Most conspicuously, the investigation of antibacterial activities demonstrated that both complexes had good activity against two selected bacteria strains. Density functional theory (DFT) by B3LYP method was used to obtain optimizations, frontier molecular orbital energies and electrostatic potential (ESP) of both complexes. On the basis of optimized geometries, time-dependent DFT (TD-DFT) recorded the specific electronic transitions in the UV-Vis spectra. In addition, the non-covalent interactions in 1 and 2 were analyzed by Hirshfeld surface analysis (HSA). [ABSTRACT FROM AUTHOR]

• [Bi(L) 2 (NO 3) 3 ] was characterized by spectroscopic methods and single-crystal X-ray diffraction. • The Bi(III) complex demonstrated different fluorescence behaviors in several diverse solvents. • The activity experiment showed antibacterial property of the complex was better than the ligand. • The optimized geometry, electronic distribution of HOMO-LUMO were studied by DFT calculation. • ESP and HAS visualized the charge distribution on the molecule and non-covalent interactions. A novel complex [Bi(L) 2 (NO 3) 3 ] (L = 2-(4-imidazolyl)-4-methyl-1,2-dihydroquinazoline-N3-oxide) was synthesized via complexation of the quinazoline ligand L with Bi(III) nitrate pentahydrate in methanol and ethyl acetate. The structure of complex was determined by elemental analysis, FT-IR, UV–vis and fluorescence spectroscopy, as well as characterized by X-ray crystallography. Crystallographic analysis divulged that the central atom Bi(III) was coordinated with eight atoms and the ratio of ligand-to-metal was 2:1. Specially, it fostered into an infinite 1-D chain, 2-D layered and ladder-like 3-D supramolecular skeleton through different intermolecular interactions. In addition, the fluorescence behaviors of Bi(III) complex in six solvents of diverse polarities were quite different. The DFT/B3LYP theoretical level has been successfully applied to calculate the optimized geometry, electronic distribution of HOMO-LUMO and the electrostatic potential diagram of Bi(III) complex. Meanwhile, the electronic transitions recorded by TD/DFT calculation theoretically rationalized the UV–vis spectrum data. The antibacterial activity of Bi(III) complex against Escherichia coli and Staphylococcus aureus were further studied. Plausible non-covalent interactions were quantified using Hirshfeld surfaces and 2D fingerprint plots. A new 1D, 2D, 3D supramolecular Bi(III) complex, [Bi(L) 2 (NO 3) 3 ], was synthesized and characterized by X-ray crystallography and spectroscopic methods. The octa-coordinated Bi(III) complex formed an infinite 1-D chain, 2-D layered and ladder-like 3-D supramolecular skeleton. The optimal geometry, frontier molecular orbital energies and electrostatic potential (ESP) of Bi(III) complex were calculated using DFT/B3LYP. The electronic distribution of HOMO-LUMO rationalized the results of UV–vis spectrum through TD/DFT calculation. All tested compounds showed a certain degree of activity against Escherichia coli and Staphylococcus aureus. Non-covalent interactions of complex were quantified with Hirshfeld surfaces using the CrystalExplorer17 program. [Display omitted] [ABSTRACT FROM AUTHOR]