Mykola P. Shandura

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.

Metallochromic merocyanines of 8-hydroxyquinoline series. II. Dyes with end nuclei of low basicity

Based on 5-substituted 8-hydroxyquinoline, a number of complexing merocyanines with the end nuclei of low basicity have been synthesized. Dyes of this kind exhibit the most pronounced metallochromic effects manifested by drastic bathochromic and hyperchromic shifts on complexation with the salts of heavy and transition metals as well as lanthanide salts. The spectral effects observed are of a complicated character and arise from the interaction of the dye, metal, and solvent.

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.

A dioxaborine cyanine dye as a photoluminescence probe for sensing carbon nanotubes

The unique properties of carbon nanotubes have made them the material of choice for many current and future industrial applications. As a consequence of the increasing development of nanotechnology, carbon nanotubes show potential threat to health and environment. Therefore, development of efficient method for detection of carbon nanotubes is required. In this work, we have studied the interaction of indopentamethinedioxaborine dye (DOB-719) and single-walled carbon nanotubes (SWNTs) using absorption and photoluminescence (PL) spectroscopy. In the mixture of the dye and the SWNTs we have revealed new optical features in the spectral range of the intrinsic excitation of the dye due to resonance energy transfer from DOB-719 to SWNTs. Specifically, we have observed an emergence of new PL peaks at the excitation wavelength of 735 nm and a redshift of the intrinsic PL peaks of SWNT emission (up to 40 nm) in the near-infrared range. The possible mechanism of the interaction between DOB-719 and SWNTs has been proposed. Thus, it can be concluded that DOB-719 dye has promising applications for designing efficient and tailorable optical probes for the detection of SWNTs.

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.