title: Photoinduced release of Zn2+ with ZinCleav-1: a nitrobenzyl-based caged complex.
abstract: Caged complexes are metal ion chelators that release analytes when exposed to light of a specific wavelength. The synthesis and properties of ZinCleav-1, a cage for Zn(2+) that fragments upon photolysis, is reported. The general uncaging strategy involves integrating a nitrobenzyl group on the backbone of the ligand so that a carbon-heteroatom bond is cleaved by the photoreaction. The caged complex was obtained using a new synthetic strategy involving a Strecker synthesis to prepare a key aldehyde intermediate. ZinCleav-1 has a K(d) of 0.23 pM for Zn(2+) as measured by competitive titration with [Zn(PAR)(2)] (PAR = 4-(2-pyridyl-2-azo) resorcinol). The quantum yield for ZinCleav-1 is 2.4% and 0.55% for the apo and Zn(2+) complex, respectively. The ability of ZinCleav-1 to increase free [Zn(2+)] is calculated theoretically using the binding constants for the uncaged photoproducts, and demonstrated practically by using a fluorescent sensor to image the liberated Zn(2+). Free Zn(2+) may function as a neurotransmitter and have a role in the pathology of several neurological diseases. Studying these physiological functions remains challenging because Zn(2+) is silent to most common spectroscopic techniques. We expect ZinCleav-1 to be the first in a class of caged complexes that will facilitate biological investigations.
authors.affiliation: Department of Chemisty, University of Connecticut, 55 North Eagleville Road U- 3060, Storrs, Connecticut 06269.
authors.forename: H M Dhammika
authors.initials: HM
authors.lastname: Bandara
authors.forename: Daniel P
authors.initials: DP
authors.lastname: Kennedy
authors.forename: Elif
authors.initials: E
authors.lastname: Akin
authors.forename: Christopher D
authors.initials: CD
authors.lastname: Incarvito
authors.forename: Shawn C
authors.initials: SC
authors.lastname: Burdette
mesh_terms: D008027:Light; D015394:Molecular Structure; D009578:Nitrobenzenes / Q000737:chemistry*; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D010777:Photochemistry; D015032:Zinc / Q000737:chemistry*
chemical_list: D009578:Nitrobenzenes; D009942:Organometallic Compounds; C036077:nitrobenzene; D015032:Zinc