A styryl dye with a chromophore based on methyl-benzothiazolium and 1-methyl-4-phenylpiperazine end group was synthesized under new improved reaction conditions. The synthesis was carried out in a way that ensured the direct production of a pure (>98 %) dye. The dye exhibits pronounced vertical and horizontal solvatochromism in both light absorption and fluorescence spectra. In the UV–Vis spectra of the dye, a difference in the longest wavelength absorption maximum from dichloromethane to water of about 100 nm was observed. In buffer (pH = 7.2), the dye absorbs at 445 nm, and in dichloromethane at 547 nm. The interaction of the dye with DNA and with protons and various metal ions was investigated, and the ability of the target fluorochrome to be used as a logic gate in the simultaneous presence of H⁺ and DNA was demonstrated. The dye is sensitive in the presence of mercury ions as well.

Three new series of 3-(substituted)methylthio-4-cyano-5,6,7,8-tetrahydroisoquinolines were designed and synthesized starting from readily available materials, 7-acetyl-4-cyano-1,6-dimethyl-6-hydroxy-8-(4-pyridyl, 3-pyridyl, phenyl, 4-methoxyphenyl, or 4-chlorophenyl)-5,6,7,8-tetrahydrosoquinoline-3(2H)-thiones 2a–e in high yields and very pure states. Thus, compounds 2a–e were reacted with some chloro reagents, namely, N-aryl-2-chloroacetamides 3a–f and N-(naphthalen-2-yl)-2-chloroacetamide (3g) under mild basic conditions to give the first two series of the target compounds, 3-(N-aryl)carbamoylmethylthio-5,6,7,8-tetrahydroisoquinoline-4-carbonitriles 4a–l and 5a–e, respectively. Reaction of compounds 2d,e with ethyl chloroacetate under the same conditions gave the other series, 3-ethoxycarbonyl-methylthio-5,6,7,8-tetrahydroisoquinoline-4-carbonitriles 6d,e. Structural formulas of all of the new compounds were elucidated and confirmed by elemental and spectral analyses. The insecticidal activity of all synthesized 5,6,7,8-tetrahydrosoquinolines toward the nymphs and adults of Aphis gossypii were screened. The results revealed the promising insecticidal activity of some tested compounds. Moreover, the structure–activity relationships as well as molecular docking of some representative compounds were evaluated.

 new water-soluble polyamidoamine (PAMAM) dendrimer modified with 4-sulfo-1,8-naphthalimide (DSNI) and its monomeric structural analogue (MSDI) were synthesized. Their photophysical properties were investigated in organic solvents of different polarities and aqueous solutions. The effect of pH on fluorescence intensity was determined. It was found that the dendrimer emits blue fluorescence in an acidic medium, which is quenched in an alkaline environment. This phenomenon is due to the possibility of suppression of nonradiative photoinduced electron transfer in acidic media. The influence of different metal ions (Cu²⁺, Pb²⁺, Sn²⁺, Sr²⁺, Mg²⁺, Ba²⁺, Co²⁺, Hg²⁺, Zn²⁺, Ni²⁺, Fe³⁺, Al³⁺) and anions (CN⁻, S²⁻, S₂O₅²⁻, HPO₄²⁻, H₂PO⁴⁻, F⁻, CH₃COO⁻, NO₂⁻, CO₃²⁻, SO₄²⁻) on the intensity of the emitted fluorescence was studied. Quenching was only found in the presence of Cu²⁺. This makes the dendrimer suitable for determining copper ions in water solutions in the presence of other metal ions and anions. Additionally, DSNI was used as a ligand to obtain a stable copper complex, the structure of which was investigated by electron paramagnetic resonance (EPR), infrared spectrum, and elemental analysis. Two copper ions were found to form a complex with one dendrimer. The in vitro microbiological activity of the new compounds against bacteria Pseudomonas aeruginosa and two viruses HRSV-2 and HAdV-5 was investigated. With a view to obtaining antibacterial and anti-viral textiles, cotton fabrics were treated with the three compounds, and then their activity against the same microbial strains was investigated. It was found that the microbiological activity was preserved after the application of the new compounds to the cotton fabrics.