Charge Transfer Complex betweenO-Phenylenediamine and 2, 3-Dichloro-5, 6-Dicyano-1, 4-Benzoquinone: Synthesis, Spectrophotometric, Characterization, Computational Analysis, and its Biological Applications

Abstract

UV–vis electronic absorption spectroscopy was used to investigate the new molecular charge transfer complex (CTC) interaction between electron donor O -phenylenediamine (OPD) and electron acceptor 2,3-dichloro-5,6-dicyano- p -benzoquinone (DDQ). The CTC solution state analysis was carried out by two different polarities. The stoichiometry of the prepared CTC was determined by using Job’s, photometric, and conductometric titration methods and was detemined to be 1:1 in both solvents (at 298 K). The formation constant and molar extinction coefficient were determined by applying the modified (1:1) Benesi–Hildebrand equation. The thermodynamic parameter Δ G ° result indicated that the charge transfer reaction was spontaneous.The stability of the synthesized CTC was evaluated by using different spectroscopic parameters like the energy, ionization potential, oscillator strength, resonance energy, dissociation energy, and transition dipole moment. The synthesized solid CTC was characterized by using different analytical methods, including elemental analysis, Fourier transform infrared, nuclear magnetic resonance, TGA-DTA, and powder X-ray diffraction. The biological evolution of the charge transfer (CT) complex was studied by using DNA binding and antibacterial analysis. The CT complex binding with calf thymus DNA through an intercalative mode was observed from UV–vis spectral study. The CT complex produced a good binding constant value (6.0 × 10 5 L.mol –1 ). The antibacterial activity of the CT complex shows notable activity compared to the standard drug, tetracycline. These results reveal that the CT complex may in future be used as a bioactive drug. The hypothetical DFT estimations of the CT complex supported the experimental studies.

Temperature-Dependent Semiconducting Behavior of an Organic Cocrystal Driven by the Stacking Mode of Interaction of a 4,4′-Bipyridine Molecule

“…For the bipy molecular part, all are deshielded by 1.0, 0.77, and 0.56 ppm. All the NMR spectral data are in support of the formation of H-bonded cocrystal 1 . , …”

“…In the case of 13 C NMR the carbon atoms in Figure S4 marked as g , h , i , and j for a phthalic acid molecule having δ values of 169.17, 131.22, 129.12, and 133.34 ppm, respectively, with differences in δ values of 1.57 (deshielded), 1.67 (shielded), 0.72 (deshielded), and 0.45 (shielded) ppm with respect to the phthalic acid molecule. Three other peaks marked as k , l , and m for bipy with δ values of 150.90, 121.64, and 144.85 ppm, respectively, with differences in δ values of 1.10, 0.54, and 0.05 ppm which are all deshielded with respect to the free bipy system is direct evidence for the formation of H-bonded cocrystal 2 . ,, …”

“…0.19 ppm (Figure S3), respectively, with respect to the individual free molecular system, giving evidence for the formation of cocrystal 2. 57,56,59 Another notable support for the formation of the cocrystal 2 is the presence of weak signal of a O•••H−N(ring) H-bonded proton at δ = 3.776 ppm. 56,55 Atom integral values show the molecular ratio of phthalic acid and bipy as 1:1, which matches the equivalent ratio of the starting materials.…”

“…For cocrystal 1 , with reference to Figure S6 a broad absorption band with stretching frequency (ν) 1697 cm –1 (band center) for CO group (marked as a , in Figure S2) of the carboxylic acid group of pyromellitic acid in the cocrystal 1 with respect to sharp intense band at 1712 cm –1 (band center) of the free pyromellitic acid molecule , is evidence of the presence of an H-bonded carbonyl group in the carboxylic acid part of pyromellitic acid. Another important stretching frequency at 3379 cm –1 corresponding to the weak band for a protonated (ring) N + –H bond (H-bonded) and two absorption peaks at 3445 and 3523 cm –1 , respectively, for an H-bonded O–H group and also an intense absorption band of aromatic C–H at 2934–3203 cm –1 of the carboxylic acid part of pyromellitic acid and bipy are strong support for the formation of cocrystal 1 . Very strong evidence for the formation of 1 is the strong absorption band at 2265–2723 cm –1 for the O – ···H–N + (ring) H-bonded fragment between the carboxylic acid group of pyromellitic acid and the N-containing aromatic ring of bipy molecules …”

Binding behavior and in vitro cytotoxicity of inclusion complexes between aminopterin and cucurbit[7]uril

“…The K-value of CB [7]-AMT inclusion complex could be determined by the typical Benesi-Hildebrand equation [19]: 3 Where , are the initial concentrations; A 0 and A are the absorbance of AMT within and without CB [7], respectively; and ε 0 and ε are the molar absorptivity of AMT within and without CB [7],…”