title: Synthesis and characterization of highly photoresponsive fullerenyl dyads with a close chromophore antenna-C(60) contact and effective photodynamic potential.
abstract: We report the synthesis of a new class of photoresponsive C(60)-DCE-diphenylaminofluorene nanostructures and their intramolecular photoinduced energy and electron transfer phenomena. Structural modification was made by chemical conversion of the keto group in C(60)(>DPAF-C(n)) to a stronger electron-withdrawing 1,1-dicyanoethylenyl (DCE) unit leading to C(60)(>CPAF-C(n)) with an increased electronic polarization of the molecule. The modification also led to a large bathochromic shift of the major band in visible spectrum giving measureable absorption up to 600 nm and extended the photoresponsive capability of C(60)-DCE-DPAF nanostructures to longer red wavelengths than C(60)(>DPAF-C(n)). Accordingly, C(60)(>CPAF-C(n)) may allow 2γ-PDT using a light wavelength of 1000-1200 nm for enhanced tissue penetration depth. Production efficiency of singlet oxygen by closely related C(60)(>DPAF-C(2) (M)) was found to be comparable with that of tetraphenylporphyrin photosensitizer. Remarkably, the (1)O(2) quantum yield of C(60)(>CPAF-C(2) (M)) was found to be nearly 6-fold higher than that of C(60)(>DPAF-C(2) (M)), demonstrating the large light-harvesting enhancement of the CPAF-C(2) (M) moiety and leading to more efficient triplet state generation of the C(60)> cage moiety. This led to highly effective killing of HeLa cells by C(60)(>CPAF-C(2) (M)) via photodynamic therapy (200 J cm(-2) white light). We interpret the phenomena in terms of the contributions by the extended π-conjugation and stronger electron-withdrawing capability associated with the 1,1-dicyanoethylenyl group compared to that of the keto group.
authors.affiliation: Department of Chemistry, University of Massachusetts Lowell, Lowell, MA, 01854, USA; ; Tel: (+978)-934-3663.
authors.forename: Long Y
authors.initials: LY
authors.lastname: Chiang
authors.forename: Prashant A
authors.initials: PA
authors.lastname: Padmawar
authors.forename: Joy E
authors.initials: JE
authors.lastname: Rogers-Haley
authors.forename: Grace
authors.initials: G
authors.lastname: So
authors.forename: Taizoon
authors.initials: T
authors.lastname: Canteenwala
authors.forename: Sammaiah
authors.initials: S
authors.lastname: Thota
authors.forename: Loon-Seng
authors.initials: LS
authors.lastname: Tan
authors.forename: Kenneth
authors.initials: K
authors.lastname: Pritzker
authors.forename: Ying-Ying
authors.initials: YY
authors.lastname: Huang
authors.forename: Sulbha K
authors.initials: SK
authors.lastname: Sharma
authors.forename: Divya Balachandran
authors.initials: DB
authors.lastname: Kurup
authors.forename: Michael R
authors.initials: MR
authors.lastname: Hamblin
authors.forename: Brian
authors.initials: B
authors.lastname: Wilson
authors.forename: Augustine
authors.initials: A
authors.lastname: Urbas