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CCVJ Is Not a Simple Rotor Probe

Christopher Rumble, Kacie Rich, Gang He, Mark Maroncelli

J Phys Chem A. 2012 Nov 8;116(44):10786-92.

PMID: 23098264

Abstract:

The photochemistry of the rotor probe 9-(2-carboxy-2-cyanovinyl)julolidine (CCVJ) was studied to elucidate a curious effect of fluid flow previously reported. The apparent sensitivity to fluid motion observed in CCVJ but not in the closely related molecule 9-(dicyanovinyl)julolidine (DCVJ) is found to be an indirect effect of a photoisomerization reaction. The results presented here demonstrate that it is this isomerization, rather than the commonly assumed TICT process, that confers viscosity-sensing ability on these fluorophores. In micromolar solutions in hydroxylic solvents CCVJ exists primarily in the carboxylate form. Only the E isomer of this anion is initially present in solutions prepared from the solid, but in room light such solutions rapidly achieve a photostationary state in which the E isomer and an essentially nonfluorescent Z isomer exist in comparable concentrations. The Z isomer is metastable in S(0) such that in the absence of light the solution reverts slowly to pure E. Unlike DCVJ where only a single isomer is possible, the production of long-lived photoproducts in CCVJ and other asymmetrically substituted styryenyl probes complicates their fluorescence response. Considerable care is needed when such fluorphores are used as steady-state sensors of environmental fluidity are used.

Chemicals Related in the Paper:

Catalog Number Product Name Structure CAS Number Price
AP142978185 9-(2-Carboxy-2-cyanovinyl)julolidine 9-(2-Carboxy-2-cyanovinyl)julolidine 142978-18-5 Price
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