RESUMEN
Novel compounds endowed with a high two-photon absorption (TPA) cross-section and a high singlet oxygen quantum yield, are sought after for their possible application in anti-cancer therapies. In this paper we present a prototype macromolecule bearing a distyrylbenzene dimer as TPA unit and a [60]fullerene moiety for singlet oxygen generation. Linear absorption and emission spectra are measured, to help understanding the interactions between the single molecular units. The TPA absorption properties of the distyrylbenzene alone as well as bound to the methanofullerene unit are recorded with the TPA-induced fluorescence technique. An appreciable enhancement of the TPA cross-section was observed in the molecular conjugate.Singlet oxygen generation has been detected exciting the sample both in the Vis and NIR through one- and two-photon absorption processes, respectively. Although functionalization decreases the overall singlet oxygen quantum yield of fullerene, the presence of the distyrylbenzene antenna allows two-photon generation of singlet oxygen through an energy transfer process.
RESUMEN
Functionalized distyrylbenzene analogs and , bearing a tris-(2-pyridylmethyl)amine-based receptor for Zn(2+), were synthesized by a Horner-Emmons-Wittig coupling reaction. It has been found that Zn(2+) complexation induces changes in the linear absorption spectrum that enhance a nonlinear sequential two-photon absorption of nanosecond pulses at 532 nm. This absorption was also found to depend on the nature of the substituent at the side benzene ring of the styrylbenzene structure.
Asunto(s)
Derivados del Benceno/síntesis química , Compuestos Organometálicos/química , Estirenos/química , Zinc/química , Derivados del Benceno/química , Estructura Molecular , FotonesRESUMEN
This paper presents the synthesis and two photon-induced absorption (TPA) properties of a functionalized distyrylbenzene (DSB) 1 containing a tetra-azacyclododecane (cyclen) receptor for Zn(II). The influence of Zn(II) on one- and two-photon absorption characteristics of 1 has been investigated in dimethyl sulfoxide. The experiments show that the TPA action spectrum of uncomplexed 1, at 750 nm employing nanosecond-long excitation pulses, is 5 times more intense than that of the complexed form. This moderate contrast between the bound and unbound species confirms, however, the potential of this design scheme for the development of molecular structures with enhanced sensitivity and contrast to be used as Zn(II) sensors through TPA-induced fluorescence microscopy.
Asunto(s)
Colorantes Fluorescentes/química , Compuestos Organometálicos/química , Fotones , Zinc/química , Absorción , Derivados del Benceno/química , Cationes Bivalentes , Ciclamas , Compuestos Heterocíclicos/química , Microscopía Fluorescente , Modelos Químicos , Espectrofotometría Ultravioleta , Estirenos/químicaRESUMEN
A large variation of the nonlinear transmission properties of a cyclen-based bis(styryl)benzene can be induced by a small change of the linear absorption spectrum upon Zn2+ binding. This result has been interpreted in the frame of a sequential two-photon process in which one photon is absorbed from the ground state and one photon is absorbed from an excited state.
