Among all amino acids, the three aromatic systems including phenylalanine, tyrosine, and tryptophan are known to manifest UV light absorption at the higher wavelengths. Their fluorescent properties are important for protein detection and determination of the spatial structure. Based on ab initio quantum chemical calculations, the absorption spectra in the 0-12 eV UV range of these aromatic amino acids were interpreted, and the photochemistry of the lowest-lying excited states was studied. For that, molecular ground-state geometries were determined using both the coupled-cluster single and double (CCSD) and complete active space self-consistent field (CASSCF) methods. The vertical electronic transition energies, associated oscillator strengths, and electric dipole moments of the lowest excited states were computed at the CASPT2//CASSCF level. The decay mechanisms of the lowest-energy excited states were investigated by performing minimum energy path (MEPs) computations. The results showed that the CCSD and CASSCF computations yielded similar structures. The lowest-energy S₁ state in phenylalanine and tyrosine, and S₁ and S₂ in tryptophan are mainly described by the π → π* excitation localized in the aromatic ring. Upon light absorption, the main photoresponse of the molecules is driven by the benzene, phenol, and indole chromophoric units.

In this study, we present a density functional study of four ruthenium complexes by means of UV–visible spectroscopy and Marcus theory. These molecules, [Ru^II(bipyP)(bipy)₂] (P1), [Ru^II(bipyP)(dmb)₂] (P2), [Ru^II(bipyP)(dtbb)₂] (P3), and [Ru^II(bipyP)(dnb)₂] (P4), where bipyP = 2,2′-bipyridine-4,4′-diphosphonic acid, bipy = 2,2′-bipyridine, dmb = 4,4′-dimethyl-2,2′-bipyridine, dtbb = 4,4′-di-tert-butyl-2,2′-bipyridine, and dnb = 4,4′-dinonyl-2,2′-bipyridine, are photosensitizers for applications in dye-sensitized photo-electrochemical cells (DSPECs). Because of the undetermined P4 conformation in the experiment, we modeled three P4 conformers with straight (P4-straight) and bent nonyl chains (P4-bend1 and bend2). UV–vis absorption spectra by time-dependent density functional theory showed intense metal-to-ligand charge transfer to anchor bipyridine ligands (MLCT-anchoring) at 445–460 nm, which accurately reproduce experimental data. The largest light-harvesting efficiency of the MLCT-anchoring state was observed in the P4-bend1 conformer, which has the lowest P4 energy. This may relate to greater electron injection in the P4 and supports experimental results of dye-only systems (do-DSPEC). The calculated charge transfer rates agree well with the experimental trend. The largest rate was obtained for P2, which was attributed to the expansion of the highest-occupied molecular orbital toward the ancillary bipy ligands and also to the short distances between dyes on the TiO₂ surface. These results also support experimental results for P2, which was the best compound for lateral hole-hopping in a sacrificial agent-containing system (sa-DSPEC).

Synthesis of propanol from propanoic acid had been done. Propanol was synthesized via two steps. They are; esterification of propanoic acid and methanol in the presence of the sulfuric acid catalyst with the mole ratio of 4:3 to produce methyl propanoate, and reduction of methyl propanoate with sodium using ethylene glycol as the solvent to yield propanol. Structural characterizations of methyl propanoate and propanol were done using IR, ¹H-NMR, and GC spectrometers. The results show that esterification of propanoic acid with methanol produced methyl propanoate in 75% yield. Reduction of methyl propanoate using ethylene glycol as a solvent produced propanol in yield of 77%.

A series of dinuclear iridium pentahydride complexes bearing chiral BINAP ligands were synthesized and characterized. The complexes can be synthesized in good yields through the hydrogenation of mononuclear precursors obtained from the reaction of [Ir­(cod)₂]­BF₄ with R-BINAP and S-BINAP. New heteroleptic dinuclear iridium complexes containing R-BINAP and S-BINAP at each iridium center could be synthesized using the proposed protocol in addition to the corresponding homoleptic dinuclear complexes. The UV–vis absorption and emission spectra as well as the CD activities have been studied. Theoretical studies of the photoexcited state of the dinuclear iridium complexes are discussed in relation to the future prospects of these compounds in photocatalysis.