Base Pair Sensitivity and Enhanced ON/OFF Ratios of DNA-Binding: Donor–Acceptor–Donor Fluorophores

Abstract

The photophysical properties of two recently reported live cell compatible, DNA-binding dyes, 4,6-bis(4-(4-methylpiperazin-1-yl)phenyl)pyrimidin-2-ol, 1, and [1,3-bis[4-(4-methylpiperazin-1-yl)phenyl]-1,3-propandioato-κO, κO']difluoroboron, 2, are characterized. Both dyes are quenched in aqueous solutions, while binding to sequences containing only AT pairs enhances the emission. Binding of the dyes to sequences containing only GC pairs does not produce a significant emission enhancement, and for sequences containing both AT and GC base pairs, emission is dependent on the length of the AT pair tracts. Through emission lifetime measurements and analysis of the dye redox potentials, photoinduced electron transfer with GC pairs is implicated as a quenching mechanism. Binding of the dyes to AT-rich regions is accompanied by bathochromic shifts of 26 and 30 nm, respectively. Excitation at longer wavelengths thus increases the ON/OFF ratio of the bound probes significantly and provides improved contrast ratios in solution as well as in fluorescence microscopy of living cells.

Meta‐Dimethoxy‐Substituted Difluoroboron Dibenzoylmethane Poly(Lactic Acid) Nanoparticles for Luminescence Anisotropy

“…We exploited the fluorescence anisotropy of boron nanoparticle luminescence to investigate the organization of fluorophores within the nanoparticles, the orientation of the absorbing and emitting dipoles, and the importance of energy migration within the nanoparticles. Understanding changes in fluorescence anisotropy based on dye concentrations and orientation in a well‐understood environment such as polylactide, can inform and better predict results in complex biological systems, such as cell membranes, proteins, or DNA …”

“…Understanding changes in fluorescence anisotropy based on dye concentrations and orientation in a well-understood environment such as polylactide, can inform and better predict results in complex biological systems, such as cell membranes, [23,24] proteins, [25] or DNA. [26]…”

Expeditious and Convenient Synthesis of Polycyclic Difluoroboron Complexes of 2‐Oxoindoline‐3‐carboxamides by Tandem Reaction

“…By installing different substituted conjugative groups, large molar emission ratios and high quantum yields could be realized for the BF 2 complexes of β‐diketonates, which could serve as photochemical reagents, two‐photon materials, and near‐IR probes 2–5. Recently, various BF 2 complexes of β‐diketonates,2–5 β‐keto esters,6 and β‐keto amides7 have been synthesized and extensively studied. However, an investigation of malonamide‐type BF 2 complexes is very rare 8…”

“…Difluoroboron (BF 2 ) complexes of N,N‐ and N,O‐based ligands are generally highly fluorescent substances in the solution, film, and solid state 1. Recently, difluoroboron complexes of β‐dicarbonyl compounds have been widely investigated 2–5. β‐Diketonates, possessing two carbonyls, can easily react with boron trifluoride etherate (BF 3 ⋅OEt 2 ) to form six‐membered heterocyclic difluoroboron complexes.…”

“…β‐Diketonates, possessing two carbonyls, can easily react with boron trifluoride etherate (BF 3 ⋅OEt 2 ) to form six‐membered heterocyclic difluoroboron complexes. By installing different substituted conjugative groups, large molar emission ratios and high quantum yields could be realized for the BF 2 complexes of β‐diketonates, which could serve as photochemical reagents, two‐photon materials, and near‐IR probes 2–5. Recently, various BF 2 complexes of β‐diketonates,2–5 β‐keto esters,6 and β‐keto amides7 have been synthesized and extensively studied.…”