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Novel BF2‐β‐diketonate complexes 1–4 bearing phenylboronic acid moieties and methoxyphenyl or dimethylaminophenyl groups were synthesized and their photophysical properties, pH response, and reactivity to D‐fructose were evaluated. Complexes 1 and 2 bearing a methoxyphenyl group luminesced with high intensity in a range of non‐polar to polar solvents, except in DMSO, whereas complexes 3 and 4 containing a dimethylaminophenyl group with twisted intramolecular charge transfer (TICT) properties showed a dramatic decrease in luminescence intensity with increasing solvent polarity. The luminescence intensity of complexes 1 and 2 decreased with increasing pH due to intermolecular vibration which associated with hydrogen bonding between the complexes and solvent water molecules, whereas it increased when they reacted with D‐fructose due to the suppression of the intermolecular vibration. In contrast, the luminescence intensity of complexes 3 and 4 increased with increasing pH and upon reaction with D‐fructose due to the loss of its TICT properties. The photophysical properties of complexes 1–4 and the TICT properties of complexes 3 and 4 were supported by density functional theory calculations. [ABSTRACT FROM AUTHOR]

The photoreactions of the chromium(III) octaethylpoprhyrin complex, [Cr(OEP)(Cl)(L)] (L = H2O, Py, OPPh3), in dichloromethane are studied using laser flash photolysis technique. A limited dissociative mechanism, including [Cr(OEP)(Cl)] as an intermediate, is ascribed to the photoinduced axial ligand substitution reactions of [Cr(OEP)(Cl)(L)] in solution based on the rate law and kinetic parameters of the reaction.

Research has been conducted on the porphyrin sitting-top complexes. The formation of these complexes with the copper(II) ion has been confirmed spectrophotometrically in aqueous acetonitrile and the formation rates determined as the water concentration function have been determined.

A study of (chloro)(pyridine)(5, 10, 15, 20-tetraphenylporphyrinato)chromium(III), [Cr(TTP)(Cl)(Py)], in both dichloromethane and toluene containing water using laser photolysis is presented. The results show that the direct ligand exchange reaction of the axial HO-H...Py in [Cr(TTP)(Cl)(HO-H...PY)] with exogenous Py does not occur as the hydrogen bond, HO-H...Py, increases the basicity of H2O.

The reactive excited state for photodissociation and the association mechanisms of CN-R to both Cl(H2O)Cr(super III)TPP and the five-coordinate ClCr(super III)TPP were investigated in laser-photolysis experiments. Experimental results showed that chloroaquachromium(III) tetraphenylporphyrin undergoes reversible reaction with isocyanide to form Cl(CN-R)Cr(super III)TPP in toluene solutions containing 4.4 x 10(super -3) M H2O and CN-R. The photodissociation of CN-R from Cl(CN-R)Cr(super III)TPP results in Cl(H2O)Cr(super III)TPP with a quantum yield ca. 0.1.

The rate constants for a boronate ion are determined for the first time by using the reaction systems of 3-nitrophenylboronic acid with ethylene glycol (EG) and propylene glycol (PG) in an alkaline solution. The reaction rate constants of a boronate ion with aliphatic diols have shown that they are much smaller than those of boronic acid, which breaks down the fixed idea that a boronate ion reacts much faster than its conjugate boronic acid.

Precise kinetic study on the reaction of boronic acid with 2,2'-biphenol and 2,3-dihydroxynaphthalene in a neutral-alkaline solution is demonstrated. The findings reveal that trigonal boronic acid is always a reactive species irrespective of the pH of the solution.

Research has been conducted on chromium(III) porphyrin complexes of octaethylporphyrin and tetramethylporphyrin. The authors report the results of the nanosecond photopysis study carried out for these complexes in toluene containing water.

The UV-vis absorption spectra and the formation kinetics of sitting-atop (SAT) complexes (M(H(sub 2)tpp)(super 2+)) of 5,10,15,20-tetraphenylporphyrin (H2tpp) with a series of divalent metal ions (M(super 2+) = Mn(super 2+), Fe(super 2+), Co(super 2+), Ni(super 2+), Cu(super 2+), and Zn(super 2+)) in acetonitrile are examined. The subsequent formation of the corresponding metalloporphyrins by deprotonation of the SAT complex and oxidation of the M(super 2+) center, of which the dynamic behavior was significantly different for the different M(super 2+) ions was observed.

Six-coordinate [Cu(pdt)2(H2O)2]2+ and four-coordinate [Cu(pdt)2]+ complexes were synthesized and the cross redox reactions were studied in acetonitrile (pdt = 3-(2-pyridyl)-5,6-diphenyl-1,2,4-triazine). Single crystal analyses revealed that [Cu(pdt)2(H2O)2](BF4)2 was of pseudo-D2h symmetry with two axial water molecules and two symmetrically coordinated equatorial pdt ligands, while the coordination structure of [Cu(pdt)2]BF4 was a squashed tetrahedron (dihedral angle = 54.87°) with an asymmetric coordination by two pdt ligands: one pdt ligand was coordinated to Cu(i) through pyridine-N and triazine-N2 while another pdt ligand was coordinated through pyridine-N and triazine-N4, and a stacking interaction between the phenyl ring on one pdt ligand and the triazine ring on another pdt ligand caused the squashed structure and non-equivalent Cu–N bond lengths. The cyclic voltammograms for [Cu(pdt)2(H2O)2]2+ and [Cu(pdt)2]+ in acetonitrile were identical to each other and quasi-reversible. The reduction of [Cu(pdt)2(H2O)2]2+ by decamethylferrocene and the oxidation of [Cu(pdt)2]+ by [Co(2,2′-bipyridine)3]3+ in acetonitrile revealed that both cross reactions were sluggish through a gated process (the structural change took place prior to the electron transfer) accompanied by slow direct electron transfer processes. It was found that the triazine ring of the coordinated pdt ligand rotates around the C–C bond between the triazine and pyridine rings with the kinetic parameters k = 51 ± 5 s−1 (297.8 K), ΔH‡ = 6.2 ± 1.1 kJ mol−1 and ΔS‡ = −192 ± 4 J mol−1 K−1. The electron self-exchange process was directly measured using the line-broadening method: kex = (9.9 ± 0.5) × 104 kg mol−1 s−1 (297.8 K) with ΔH‡ = 44 ± 7 kJ mol−1 and ΔS‡ = 0.2 ± 2.6 J mol−1 K−1. By comparing this rate constant with the self-exchange rate constants estimated from the cross reactions using the Marcus cross relation, the non-adiabaticity (electronic) factors, κel, for the direct electron transfer processes between [Cu(pdt)2]+/2+ and non-copper metal (Fe2+ and Co3+) complexes were estimated as ca. 10−7, indicating that the electronic coupling between the d orbitals of copper and of non-copper metals is very small. [ABSTRACT FROM AUTHOR]