Ruslan Guliyev

Selective manipulation of ICT and PET Processes in styryl-Bodipy derivatives: applications in molecular logic and fluorescence sensing of metal ions.

Remarkably versatile chemistry of Bodipy dyes allows the design and straightforward synthesis of multivalent-multitopic derivatives, which, with judicious selection of metal ion-ligand pairs based on known affinities, affords control and manipulation of photoinduced electron transfer and internal charge transfer processes as desired. We have demonstrated that metal ions acting as modulators (or inputs, in digital design parlance) can generate absorbance changes in accordance with the operation of a half-adder. In addition, an AND logic gate in the emission mode was delivered using a different binucleating arrangement of ligands. A molecular equivalent of a three-input AND logic gate was also obtained exploiting differential binding affinities of metal ions for different ligands. The results suggest that different metal ions can be used as nonannihilating inputs, selectively targeting various ligands incorporated within a single fluorophore, and with careful design, diverse photophysical processes can be selectively modulated, resulting in a range of signals, useful in molecular logic design, and offering an enticing potential for multianalyte chemosensors.

Design strategies for ratiometric chemosensors: modulation of excitation energy transfer at the energy donor site.

Excitation energy transfer, when coupled to an ion-modulated ICT chromophore, creates novel opportunities in sensing. The direction of energy transfer and the point of ICT modulation can be varied as desired. In our previous work, we have shown that energy transfer efficiency between two energetically coupled fluorophores will be altered by the metal ion binding to the ICT chromophore carrying a ligand. There are two beneficial results: increased pseudo-Stokes shift and expanded dynamic range. Here, we explored the consequences of the modulation of energy transfer efficiency at the energy donor site, in a molecular design which has an ICT type metal ion-sensitive chromophore placed as the energy donor in the dyad. Clear advantages emerge compared to the acceptor site modulation: unaltered emission wavelength in the red end of the visible spectrum, while keeping a large Stokes shift and the ratiometric character.

Expanded Bodipy Dyes: Anion Sensing Using a Bodipy Analog with an Additional Difluoroboron Bridge

Oxalyl-tethered pyrroles can be doubly bridged with two difluoroboron chelating units to yield bright orange dyes. Interestingly, in polar organic solvents, the addition of fluoride and cyanide result in reversible detachment of the otherwise stable difluoroboron bridges, resulting in sharp changes in color. Thus, this novel compound behaves as a highly selective chromogenic sensor for fluoride and cyanide ions.

Designing an Intracellular Fluorescent Probe for Glutathione: Two Modulation Sites for Selective Signal Transduction

A selective probe for glutathione was designed and synthesized. The design incorporates spatial and photophysical constraints for the maximal emission signal. Thus, pHs, as well as the intracellular thiol concentrations, determine the emission signal intensity through a tight control of charge-transfer and PeT processes. The probe works satisfactorily inside the human breast adenocarcinoma cells, highlighting GSH distribution in the cytosol.

Near-IR-triggered, remote-controlled release of metal ions: a novel strategy for caged ions.

A ligand incorporating a dithioethenyl moiety is cleaved into fragments which have a lower metal-ion affinity upon irradiation with low-energy red/near-IR light. The cleavage is a result of singlet oxygen generation which occurs on excitation of the photosensitizer modules. The method has many tunable factors that could make it a satisfactory caging strategy for metal ions.

Ion responsive near-IR BODIPY dyes: two isomers, two different signals

Tetrastyryl-substituted BODIPY dyes are likely to evolve into a new class of near IR fluorophores. In this work we demonstrate that 1,7 and 3,5-positions show marked differences in charge transfer characteristics. Using a Hg(II) selective ligand, the signal transduction potentials were explored: one isomer shows a large blue shift in electronic absorption spectrum, while the other just shows an intensity increase in the emission spectrum. Electronic structure calculations were undertaken to elucidate the reasons for different signals on metal ion binding in relation to core BODIPY properties.

Energy Harvesting in a Bodipy-Functionalized Rotaxane

A rotaxane composed of two separate Bodipy-functionalized units can be synthesized with a high yield. The resulting structure shows a very efficient through-space energy transfer (FRET), acting as an energy funnel. Thus, maximum solar output in the visible region can be collected and converted into red light, which can be transformed efficiently with a fine-tuned photovoltaic device. The versatility of the synthetic pathway demonstrates the potential utility of rotaxane-based energy harvesting supramolecules assemblies.