New Triphenylphosphonium Salts of Spiropyrans: Synthesis and Photochromic Properties.

The most important area of modern pharmacology is the targeted delivery of drugs, and one of the most promising classes of chemical compounds for creating drugs of this kind are the photochromic spiropyrans, capable of light-controlled biological activity. This work is devoted to the synthesis and study of the photochromic properties of new triphenylphosphonium salts of spiropyrans. It was found that all the synthesized cationic spiropyrans have high photosensitivity, increased resistance to photodegradation and the ability for photoluminescence.

Application of Sonotriboluminescence to Determine Arene Molecules in Hydrocarbons.

The sonotriboluminescence of suspensions of terbium(III) and europium(III) sulfates in decane without and in the presence of benzene, toluene and p-xylene was studied. The choice of crystals of these lanthanides is due to the fact that they have intense luminescence during mechanical action, and also do not dissolve in hydrocarbon solvents. During ultrasonic exposure to suspensions in pure alkanes, bands of Ln3+ ions and N2 in the UV region are recorded in the luminescence spectrum. When aromatic hydrocarbon molecules are added, bands of benzene, toluene and p-xylene molecules, coinciding with their photoluminescence spectra, are recorded in the sonotriboluminescence spectra in the UV region. The high sensitivity of the luminescence of suspensions to arene additives made it possible to obtain the dependence of the characteristic fluorescence of arene molecules in the sonotriboluminescence spectra on their concentration in suspensions. The limits of detection of benzene, toluene and p-xylene in the composition of this suspension were established. The lower limits of detection from the sonotriboluminescence spectra for xylene, toluene and benzene are 0.1, 3 and 50 ppmv, respectively. Fluorescence bands of these molecules were also recorded in the sonotriboluminescence spectra of suspensions in commercial dodecane and heptane with additives of commercial gasoline (up to 1%). The results obtained can be used for luminescent detection of aromatic compounds in saturated hydrocarbons.

Photoluminescence and mechanoluminescence of solid-state zirconocene dichlorides.

Spectral-luminescence properties of 23 samples of zirconium complexes were studied. Mechanoluminescence spectra of 10 complexes were obtained. The solid-state component of the mechanoluminescence spectrum, that is the luminescence of the crystal itself, coincided with the photoluminescence spectra of these complexes, which indicated identical emission from the same excited states in mechanoluminescence and photoluminescence, despite the different ways of excitation. The luminescence maximum was red shifted as substituents appeared in the ligand, in particular in the presence of a bridging group connecting π-ligands (ansa-complexes) and also for a substituted bis-indenyl complex rac-Me2 Si(2-Me-4-Ph-5-OMe-6-But -Ind)2 ZrCl2 ). It was found that mechanical destruction of the rac-isomer of complex Mе2 С(2-Me-4-But -C5 H2 )2 ZrCl2 , unlike that of the meso-isomer, was accompanied by a more than a 10-fold increase in intensity and by a shift in the mechanoluminescence spectrum to longer wavelengths.

Mechanoluminescence of Ce/Tb inorganic salts in methane-acetylene mixtures with inert gases.

The mechanoluminescence of cerium (Ce) and terbium (Tb) lanthanide salts is studied in hydrocarbon [methane (CH4 ) and acetylene (C2 H2 )] and inert [helium (He), neon (Ne), argon (Ar), krypton (Kr), and xenon (Xe)] gaseous mixtures. The lines of *N2 , *Ln3+ , inert gases, *CH, and *C2 radicals resulted from the mechanochemical decomposition of CH4 and C2 H2 are observed in the emission spectrum. The luminescence intensity of the inert gases decreases with the hydrocarbon gas concentration in the mixture. The intensities of the *CH or *C2 bands remains almost unchanged within 15-100 vol% of CH4 or C2 H2 in the mixture. When the concentration of CH4 or C2 H2 is lower than 15%, the intensities of the CH or C2 bands increase achieving their maxima at 0.5-3% of the hydrocarbon. This is probably due to the optimal compositions of the mixtures with the most efficient generation of electrical discharges responsible for mechanoluminescence.

Luminescence of Aromatic Compounds During Ultrasonic Treatment of Tb2(SO4)3 Suspension in Commercial Gasoline.

The spectral-luminescent properties of a suspension of terbium sulfate in commercial gasoline under sonication are studied. The following emitters are identified from the luminescence spectrum: *Tb3+ ions in crystals, electronically excited molecules of arenes (benzene, toluene, and xylenes), and polycyclic aromatic hydrocarbons (PAHs) in the liquid phase of the suspension. The study of sonotriboluminescence in gasoline-heptane and heptane-xylene-PAH synthetic mixtures shows for the first time that there is an effective luminescence activator in gasoline, that is, terphenyl molecules. It has been established that these molecules have the highest luminescence yield among all sonotriboluminescence emitters found. This is provided by the transfer of the excitation energy from monocyclic arene molecules primarily excited during the sonication. In this case, the primary excitation of aromatic hydrocarbon molecules in commercial gasoline during the ultrasonic treatment of suspensions occurs under the impact of charged particles/electrons generated during electrical discharges initiated by collision and destruction of microcrystals. This process is similar to radioluminescence excitation in liquid scintillators which can be considered commercial gasoline. The formation of *Tb3+ is due to separation and recombination processes of charges that populate the excited states of luminescence centers in microcrystals electrified during tribodestruction under sonication of the suspension.

Luminescence of aromatic hydrocarbon molecules in the sonication of terbium sulfate suspensions.

The sonication of terbium sulfate suspensions in benzene, toluene, and p-xylene induces intense UV luminescence (260-320 nm). The luminescence bands coincide with the fluorescence spectra of these aromatic hydrocarbons, but it is not observed in their sonoluminescence spectra. Furthermore, the spectra of ultrasound-initiated luminescence of the suspensions defined as sonotriboluminescence, which is 103 times more intense than the sonoluminescence of hydrocarbons, exhibit also emission from the ∗Tb3+ ion. The luminescence of ∗N2, which is observed during traditional triboluminescence of terbium sulfate in air, is hardly detectable in the case of sonolysis of terbium sulfate suspensions in aromatic hydrocarbons, but can be observed on decreasing the temperature of the suspensions, which decreases the saturated vapor pressure of the liquids. A possible mechanism of excitation of aromatic hydrocarbon molecules during sonotriboluminescence is discussed.

Sonochemically assisted 2,3-dideoxygenation and skeletal rearrangement of ecdysteroid derivatives.

Sonochemical 2,3-dideoxygenation of ecdysteroids with the Δ 2(3)-bond generation and activation of the C-C bonds of the steroid core in the poststerone derivatives, that causes the skeletal rearrangement have been carried out for the first time. Thus, the ultrasonically assisted reaction of 2,3-dimesyloxy derivatives of ecdysteroids with the NaI-Zn-DMF system gives rise to their 2,3-dideoxy-Δ2(3)-analogues with yields 70-92%. In the case of 2,3-dimesyloxypoststerone as the initial ecdysteroid substrate the reaction is accompanied by the activation of the allyl moiety and semipinacol rearrangement, resulting in the C13-C14 bond migration with C/D rings contraction/expansion and providing novel short chain (8R)-13(14 → 8)-abeo-isomer.