Computational Design of Two-Photon Fluorescent Probes for a Zinc Ion Based on a Salen Ligand

Abstract

A two-photon fluorescent probe has become a critical tool in biology and medicine owing to its capability of imaging intact tissue for a long period of time, such as in two-photon fluorescence microscopy (TPM). In this context, a series of Salen-based zinc-ion bioimaging reagents that were designed based on an intramolecular charge-transfer mechanism were studied through the quantum-chemical method. The increase of one-photon absorption and fluorescence emission wavelength and the reduction of the oscillator strength upon coordination with a zinc ion reveal that they are fluorescent bioimaging reagents used for ratiometric detection. When the Salen ligand is incorporated with Zn(2+), the value of the two-photon absorption (TPA) cross-section (δmax) will decrease, and most of the ligands and complexes exhibit a TPA peak in the near-infrared spectral region. That is, a substituent at the end of the ligand can influence the luminescence property, besides increasing solubility. In addition, the effect of an end-substituted position on the TPA property was considered, such as ortho and meta substitution. The detailed investigations will provide a theoretical basis to synthesize zinc-ion-responsive two-photon fluorescent bioimaging reagents as powerful tools for TPM and biological detection in vivo.

Construction of an orthogonal ZnSalen/Salophen library as a colour palette for one- and two-photon live cell imaging

“…28,29 a1s1-a1s10 have an intense band at 550-700 nm, ascribed to an intramolecular charge-transfer transition. 26,30,31 These are different from the corresponding analogues containing the diamines a2-a11. To examine how the aromatic diamine moiety inuences the photophysical properties of the ZnSalen/Salophen complexes, the absorption spectra of a3s1-a6s1 and a2s1, a7s1-a11s1 are shown in Fig.…”

“…ZnSalen/Salophen complexes have been shown to possess high two-photon absorption (2PA) cross sections and applied in two- photon uorescence spectroscopy. 14,30 To understand the relationship between the 2PA cross section and the electronic structure, we measured 2PA cross sections of a1s1, a1s10 and a3s1-a11s1 by the two-photon induced uorescence method referenced to Rhodamine B. 34 As shown in Fig.…”

π-Extended diketopyrrolopyrrole–porphyrin arrays: one- and two-photon photophysical investigations and theoretical studies

“…[60][61][62][63][64][65][66][67][68][69][70][71][72][73][74][75] Understanding the structural-photophysical properties relationships of p-extended porphyrins on the basis of both experimental and theoretical analysis is of considerable interest to optimize the design of efficient molecules characterized by NIR absorption and fluorescence, high triplet yield and high TPA cross-sections, as good candidates for both linear and non-linear biomedical applications. [76][77][78][79][80][81] Theoretical analysis based on OPA and TPA simulated spectra and on calculated emission will enable us to extract the electronic properties at the origin of photophysical processes not directly accessible experimentally. Diketopyrrolopyrrole (DPP) is a red pigment, which was advantageously associated with porphyrins for dye-sensitized solar cells and material sciences applications.…”

A theoretical investigation of the two-photon absorption and fluorescent properties of coumarin-based derivatives for Pd2+ detection

“…1 14 So far, although there are some theoretical and experimental reports for TP uorescent probes, [22][23][24][25][26][27] there have been no theoretical research reports of TP probes based on Pd 2+ -triggered chemical catalytic reactions and coumarin derivatives, and the relationship between the molecular structure and nonlinear absorption properties of coumarin derivatives is still unclear. This study is devoted to providing some strategies for designing a series of novel TP molecules based on coumarin cores, shown in Fig.…”