TY - JOUR

T1 - Solvent Effects on Nonradiative Relaxation Dynamics of Low-Energy Ligand-Field Excited States

T2 - A CuCl42- Complex

AU - Mereshchenko, Andrey S.

AU - Myasnikoya, Olesya S.

AU - Panov, Maxim S.

AU - Kochemirovsky, Vladimir A.

AU - Skripkin, Mikhail Yu.

AU - Budkina, Darya S.

AU - Tarnovsky, Alexander N.

PY - 2017/5/4

Y1 - 2017/5/4

N2 - Nonradiative relaxation dynamics of CuCl42- complexes photoexcited into the highest-energy ligand-field electronic state ((2)A(1)) is studied in acetonitrile, dichloromethane, and chloroform solvents, as well as in acetonitrile water and in acetonitrile deuterated water mixtures. Due to ultrafast internal conversion, this excited state directly converts to the electronic ground state in dichloromethane and chloroform. The nonradiative relaxation constant is similar in anhydrous acetonitrile. Addition of water to acetonitrile solutions efficiently quenches the excited ligand-field 2A1 state. The quenching is proposed to be due to the diffusion-controlled formation of an electronically excited pentacoordinated [CuCl4H2O](2-) encounter complex or a short-lived exciplex of similar structure, in which the electronic excitation energy transfers into the O-H stretch of the coordinated H2O molecule. This is followed by the dissociation of the pentacoordinated species, resulting in the reformation of the ground-state CuCl42- and free H2O molecules.

AB - Nonradiative relaxation dynamics of CuCl42- complexes photoexcited into the highest-energy ligand-field electronic state ((2)A(1)) is studied in acetonitrile, dichloromethane, and chloroform solvents, as well as in acetonitrile water and in acetonitrile deuterated water mixtures. Due to ultrafast internal conversion, this excited state directly converts to the electronic ground state in dichloromethane and chloroform. The nonradiative relaxation constant is similar in anhydrous acetonitrile. Addition of water to acetonitrile solutions efficiently quenches the excited ligand-field 2A1 state. The quenching is proposed to be due to the diffusion-controlled formation of an electronically excited pentacoordinated [CuCl4H2O](2-) encounter complex or a short-lived exciplex of similar structure, in which the electronic excitation energy transfers into the O-H stretch of the coordinated H2O molecule. This is followed by the dissociation of the pentacoordinated species, resulting in the reformation of the ground-state CuCl42- and free H2O molecules.

KW - TRANSIENT ABSORPTION-SPECTROSCOPY

KW - CHARGE-TRANSFER DYNAMICS

KW - ULTRAFAST PUMP-PROBE

KW - EXCIPLEX FORMATION

KW - PHOTOREDOX CHEMISTRY

KW - METHANOLIC MEDIUM

KW - CHLORO-COMPLEXES

KW - COPPER-COMPLEXES

KW - AQUEOUS-SOLUTION

KW - ACETONITRILE

U2 - 10.1021/acs.jpcb.7b02015

DO - 10.1021/acs.jpcb.7b02015

M3 - статья

VL - 121

SP - 4562

EP - 4568

JO - Journal of Physical Chemistry B

JF - Journal of Physical Chemistry B

SN - 1520-6106

IS - 17

ER -