Synthesis, crystal structure, spectral and DFT studies of potent isatin derived metal complexes

A comparison between observed and DFT calculations on structure of 5-(4-chlorophenyl)-2-amino-1,3,4-thiadiazole

“…A strong absorption band was observed at 280 nm ( f = 0.5110) and 285 nm ( f = 0.6398) in the gas and solvent phase (DMSO), which corresponds to the excitation of electrons occurred from HOMO to LUMO transition (96.71% and 97.96% orbital contribution). It could be owing to the solvent effects, which can impact the geometry, molecular properties and electrostatic structure, thus causing shift in absorption bands 39 . The electronic transitions occurred from dipolar interaction with solvents of different polarities suggest that the intramolecular charge transfer (ICT) of the emission state in which the HOMO and LUMO were apparently localized on the 1,3,4-thidiazole moiety and the phenyl ring.…”

“…The greater stabilization energy E (2) value indicates more intensive interaction amongst the electron acceptors and donors, i.e . the high electrons donating ability and superior degree of conjugation of the entire system 39 . Numerous donor and acceptor interactions were identified for the phenyl and 1,3,4-thiadiazole rings, and lone pairs (n) of the sulfur, chlorine and nitrogen atoms.…”

Macrocyclic Cr3+, Mn2+ and Fe3+ complexes of a mimic SOD moiety: Design, structural aspects, DFT, XRD, optical properties and biological activity

“…The length of N(8)‐H(11), N(31)‐H(34), N(30)‐C(21) and N(8)‐C(3) bonds enlarged slightly upon complexation due to binding to (C=N) group with formation of M‐N bond with a hybrid functional RBPE method at the DNP basis set were performed to elaborate the structure–activity relationship. It is well known that descriptors such as E HOMO , E LUMO and energy gap as well as molecular electrostatic potential (MEP) have been found to be useful in the analysis of the relationship between complex structures and biological activity . Figures c and d illustrate Frontier molecular orbitals, the HOMO and LUMO of Cr 3+ complex showing the localization of HOMO on cyclohexyl and phenyl rings while LUMO orbital localized on the coordinated macrocyclic arm i.e.…”

“…It was found that, E HOMO , −3.14 eV, and E LUMO = −2.20 eV with energy gap, ΔE = −0.94 eV, which is less than that of the macrocycle (−2.74). So, Cr 3+ complex is more efficient to be explored in a solar cell than the macrocycle itself as it possesses a small energy gap, can absorb photons of the light beam efficiently and consequently the resultant current of the circuit will be higher resulting in great efficient power conversion . Also, the small value of energy gap means the easier is the charge transfer which affects the bioactivity of a molecule that will be confirmed by the potent antibacterial activity of Cr 3+ complex later.…”

Molecular Iodine-Mediated Synthesis of 2-Azaanthraquinones from [3.3.3]Propellanes via a Metal-Free Rearrangement

“…In this study, we used the natural bond orbital (NBO) analysis to understand the delocalization of electron density, the relation between intra-and inter-molecular bonds, and charge transfer (CT) in molecular structure. 28 Delocalization of electron density between donor and acceptor is calculated by examining the stabilization energy E (2) . More intensive interaction between the electron-donors and -acceptors gives higher stabilization energy values.…”