Viktor P. Yakubovskyi

Push–pull dioxaborine as fluorescent molecular rotor: far-red fluorogenic probe for ligand–receptor interactions

Fluorescent solvatochromic dyes and molecular rotors increase their popularity as fluorogenic probes for background-free detection of biomolecules in cellulo in no-wash conditions. Here, we introduce a push-pull boron-containing (dioxaborine) dye that presents unique spectroscopic behavior combining solvatochromism and molecular rotor properties. Indeed, in organic solvents, it shows strong red shifts in the absorption and fluorescence spectra upon increase in solvent polarity, typical for push-pull dyes. On the other hand, in polar solvents, where it probably undergoes Twisted Intramolecular Charge Transfer (TICT), the dye displays strong dependence of its quantum yield on solvent viscosity, in accordance to Förster-Hoffmann equation. In comparison to solvatochromic and molecular rotor dyes, dioxaborine derivative shows exceptional extinction coefficient (120,000 M-1 cm-1), high fluorescence quantum yields and red/far-red operating spectral range. It also displays much higher photostability in apolar media as compared to Nile Red, a fluorogenic dye of similar color. Its reactive carboxy derivative has been successfully grafted to carbetocin, a ligand of the oxytocin G protein-coupled receptor. This conjugate exhibits >1000-fold turn on between apolar 1,4-dioxane and water. It targets specifically the oxytocin receptor at the cell surface, which enables receptor imaging with excellent signal-to-background ratio (>130). We believe that presented push-pull dioxaborine dye opens a new page in the development of fluorogenic probes for bioimaging applications.

A sensing mechanism for the detection of carbon nanotubes using selective photoluminescent probes based on ionic complexes with organic dyes

The multifunctional properties of carbon nanotubes (CNTs) make them a powerful platform for unprecedented innovations in a variety of practical applications. As a result of the surging growth of nanotechnology, nanotubes present a potential problem as an environmental pollutant, and as such, an efficient method for their rapid detection must be established. Here, we propose a novel type of ionic sensor complex for detecting CNTs – an organic dye that responds sensitively and selectively to CNTs with a photoluminescent signal. The complexes are formed through Coulomb attractions between dye molecules with uncompensated charges and CNTs covered with an ionic surfactant in water. We demonstrate that the photoluminescent excitation of the dye can be transferred to the nanotubes, resulting in selective and strong amplification (up to a factor of 6) of the light emission from the excitonic levels of CNTs in the near-infrared spectral range, as experimentally observed via excitation-emission photoluminescence (PL) mapping. The chirality of the nanotubes and the type of ionic surfactant used to disperse the nanotubes both strongly affect the amplification; thus, the complexation provides sensing selectivity towards specific CNTs. Additionally, neither similar uncharged dyes nor CNTs covered with neutral surfactant form such complexes. As model organic molecules, we use a family of polymethine dyes with an easily tailorable molecular structure and, consequently, tunable absorbance and PL characteristics. This provides us with a versatile tool for the controllable photonic and electronic engineering of an efficient probe for CNT detection.

Pyrrolidylsubstituted Azadipyrromethene with Fully Chelated Boron Atom

A difluorosubstituted aza-boron–dipyrromethene derivative with fully chelated boron atom was synthesized by the reaction of BF3 · Et2O with 3,3,5,5-tetraarylazadipyrromethene, which was easily prepared from 1,3-diaryl-4-nitro-butan-1-one and ammonium acetate. One fluorine atom of the dye was substituted by pyrrolidine residue. This resulted in a significant bathochromic effect. Ultraviolet absorption and fluorescence emission spectra were recorded, and quantum yields of the obtained compounds were calculated.

Boradipyrromethenecyanines on the base of a BODIPY nucleus annelated with a pyridone ring: a new approach to long-wavelength dual fluorescent probe design

A number of polymethine dyes based on a BODIPY nucleus annelated with a pyridone ring have been synthesized. The merocyanines of this series are long-wavelength and intensive dyes. Obtained for the first time, asymmetrical anionic boradipyrromethenecyanines are also interesting from another viewpoint. These compounds are able to exist in several equilibrium forms which belong to polymethine or boradipyrromethene chromophoric systems. This results in the appearance of multicomponent bands in absorption and fluorescence spectra that may be used in the design of dual fluorescent probes.

Dehydroacetic Acid Based Dioxaborine Styryl Dye: Effective Fluorescent Probe for Ammonia and Amine Detection

The newly synthesized dioxaborine dyes, derivatives of dehydroacetic acid, were tested for the detection of amines and ammonia. To discriminate the substance with efficient sensing parameters, series of ca. 20 dioxaborine dyes were synthesized and tested for reactivity with amines. The most promising one showed the fluorescent sensitivity to amines in the range of 1-4 ppm.