Sensitized photolysis of bis(acetylacetonato)copper(II); general reaction pattern

Abstract

Bis(acetylacetonato)copper(II) was sensitized by some ketones with a wide range of triplet energies to undergo photodecomposition to give the same products as that obtained in the direct photolysis but with much better efficiency. Other sensitizers such as fluorenone and aromatic hydrocarbons failed to sensitize the reaction. There exists no correlation of the sensitizer triplet energies with the sensitization results. This, and rapid quenching processes, indicated that the classical energy transfer process was unlikely. The sensitization process by an electron transfer within an encounter complex was proposed to explain the decomposition of Cu(acac)2; the calculated free energy changes (ΔG) associated with the electron transfer from the available data support the proposal. Chemical reactions of excited state anthracene and 1-cyanonaphthalene with Cu(acac)2 may also occur. Irradiation of Cu(acac)2 in the presence of triphenylphosphine and benzophenone led to an excellent yield of Cu(acac)(PPh3)2 without causing precipitation of copper(I) complexes.

Characterization of pure ZnO thin films prepared by a direct photochemical method

“…p* transition. Although the photochemistry of several transition metal 1,3-diketonates has been extensively investigated [23][24][25][26][27], no reports can be found in the literature concerning Zn complexes. We therefore carried out experiments to evaluate the photosensitivity of the Bis(1-phenyl-1,3-butanodionate)Zn(II) complex in solution and as a film.…”

Mechanistic studies of aromatic ketone-sensitized photoreduction of bis(acetylacetonato)copper(II)

“…Characteristically, the variation of k, was only within an order of magnitude in spite of large variations in ET or -ET -EAIA-; that is, the imaginary slopes were about 0.2 per eV. The resistance of diamagnetic Cu(1) complexes of triphenylphosphine, 2,2'-dipyridine, and 1,lO-phenanthroline toward the photoreduction was confirmed (1). The diamagnetic acetylacetonates of magnesium(I1) could not be photoreduced under similar benzophenone sensitization conditions, nor was the rate of benzophenone photoreduction affected.…”

“…Commercially available sensitizers were purified by distillation or recrystallization-sublimation. Other conditions are the same as those described in the previous papers (1).…”

“…sensitize the Cu(acac)? reduction efficiently, while fluorenone and p-methoxyacetophenone are totally inefficient as sensitizers (1).…”

Photoswitchable Sol–Gel Transitions and Catalysis Mediated by Polymer Networks with Coumarin‐Decorated Cu24L24 Metal–Organic Cages as Junctions

“…Solution DOSY studies of coumarin‐decorated MOCs lacking PL in the Cu II state revealed the presence of an approximately 3.9±1.5 nm species as determined from the measured diffusion coefficient and the Stokes–Einstein equation. Photoreduction led to the disappearance of these slowly diffusing species and concomitant sharpening of the signals, which is indicative of both MOC disassembly and the transition from paramagnetic Cu II to diamagnetic Cu I (Figure a) . DFT calculations of a model bis‐Cu II paddlewheel complex indicated that reduction of even one Cu center leads to cleavage of Cu–ligand bonds (Figure b) and further reduction leads to complete paddlewheel disassembly.…”