Comparative studies of multi-photon induced emission by pyridine-based small molecular probes in biological media: Selective binding of bioactive molecules and in vitro imaging

Wanqing Wu, Hoi Kuan Kong, Hongguang Li, Yu Man Ho, Yuan Gao, Jianhua Hao, Margaret B. Murphy*, Michael Hon Wah Lam, Ka-Leung WONG, Chi Sing LEE

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)

Abstract

A new class of organic molecular probes (1-3) based on a 1,3-disubstituted diethynylbenzene core has been developed. Both 1 and 2 (with the esters of 1 replaced by diethylamides in 2) show good linear and three-photon induced photophysical properties with two-photon absorption cross-sections (185-210 cm4sphoton-1molecule-1) that are suitable for biological applications in live specimens. The propeller π-conjugated systems of 3 (a C3 analogue of 1) shows threefold enhancement for the two-photon absorption cross-section (650 cm4sphoton -1molecule-1). Solvatochromism was observed in the fluorescence spectra of all these molecular probes; in acidic medium (pH = 4-5) their fluorescence emissions are slightly blueshifted with a threefold enhancement in intensity relative to those observed under basic conditions (pH = 10-11). In the fluorometric titration study against a variety of bioactive small molecules, only 2 shows strong binding affinity (log KB > 7) towards citrates and bicarbonates with approximately 30 nm redshift. The in vitro emission spectra of 2 obtained show the same emission upon addition of anions to the solution. The results of these studies could provide new molecular-design strategies for two-photo absorption (TPA) chromophores and new materials for two/multi-photon imaging in vitro. A new class of organic molecular probes has been developed, and the cell-permeable properties were improved dramatically by introducing diethylamide moieties. Only 2 shows strong emission enhancement uponbinding with citrates and bicarbonates. The emission spectra of 2 obtained in vitro show the same emission with citrate and hydrogencarbonate.

Original languageEnglish
Pages (from-to)5054-5060
Number of pages7
JournalEuropean Journal of Organic Chemistry
Issue number26
DOIs
Publication statusPublished - Sep 2011

Scopus Subject Areas

  • Physical and Theoretical Chemistry
  • Organic Chemistry

User-Defined Keywords

  • Anions
  • Fluorescent probes
  • Imaging agents
  • Luminescence
  • Photochemistry

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