Dynamics of ion-regulated photoinduced electron transfer in BODIPY-BAPTA conjugates

作者：Batat Pinar; Vives Guillaume; Bofinger Robin; Chang Ren Wei; Kauffmann Brice; Oda Reiko; Jonusauskas Gediminas^*; McClenaghan Nathan D

来源：Photochemical and Photobiological Sciences, 2012, 11(11): 1666-1674.

DOI：10.1039/c2pp25130b

Efficient Ca2+-switched fluorescent sensors, where fluorescence output is governed by a light-activated ion-gated electron transfer pathway, can be obtained on combining BODIPY chromophores with a readily oxidized biocompatible and selective BAPTA receptor. Herein we report the synthesis and studies of two such conjugates, which vary in the nature of the spacer separating the two electroactive components, namely none (1) or phenyl (2). Single crystal X-ray crystallography and molecular modelling structures and calculations give information on molecular and electronic structure, while steady-state fluorescence experiments show high Ca2+-induced fluorescence enhancement factors of 122 and 23 and K-d values of 0.50 mu M and 0.13 mu M for 1 and 2, respectively. Notably, studies of the ultrafast photoinduced processes (through transient absorption spectroscopy) give access to electron transfer dynamics in pseudo-physiological media as well as in a polar non-protic solvent and information about the fate of the excited molecules in the presence and absence of calcium. In water, electron transfer rates as high as 3.3 x 10(12) s(-1) and 8.3 x 10(11) s(-1) are measured for the ion-free, directly connected conjugate and the variant incorporating a phenyl spacer, respectively. This electron transfer pathway is efficiently blocked by the presence of an ion, restoring fluorescence.

• 出版日期2012