Alexander Shokurov

• PhD
• Postdoc at ETH Zurich

An innovative design of reusable SPR chips allowing the quantitative and selective determination of mercury(II) at ppt level is reported.

The influence of air oxygen on the processes of electrochemical reduction of double-decker 15-crown-5 substituted lanthanide phthalocyaninates in solutions and Langmuir-Blodgett films on electrode surfaces was revealed. The multistage nature of the process, associated with formation of the intermediate oxygen-containing complexes of the studied com...

In this work, a previously undescribed phenomenon of orientation-induced redox isomerism in a Langmuir monolayer is revealed in the case of cerium bis-[tetra-(15-crown-5)-phthalocyaninate] – (Ce[(15C5)4Pc]2). It was established that intramolecular electron transfer (IET) from the electronic system of phthalocyanine to the 4f-orbital of cerium atom...

A boron-capped tris-dioximate iron(II) bis-macrocyclic clathrochelate with annulated dimethylquinoxaline heterocycle has been synthesized. The compound has been characterized with single-crystal X-ray diffraction, multinuclear NMR, IR, UV-vis spectrometry, CV and spectroelectrochemistry. The clathrochelate is capable of ligand-centered two-electron...

The present work considers the possibility of increasing the information signal of thin-film sensitive element of the sensor based on amphiphilic crown substituted derivative of 4-(acylamino)-1,8-naphthalimide via employment of resonance photoexcitation energy transfer process. In such system, information signal is the fluorescence of acceptor fluo...

This work deals with the development of ultrathin film nanosensors for selective and sensitive detection of toxic Hg²⁺ cations in aqueous media. 1,8-Bis[(2-aminoethyl)amino]anthraquinone D0 was functionalized by alkoxy groups of different length to prepare ligands D3 and D12 with linear arrangement of two polyamine receptors and two lipophilic alky...

Flexible triboelectric nanogenerators (TENGs) have attracted increasing interest since their advent in 2012. In comparison with other flexible electrodes, hydrogels possess transparency, stretchability, biocompatibility, and tunable ionic conductivity, which together provide great potential as current collectors in TENGs for wearable applications....

Sulfur-containing groups preorganized on macrocyclic scaffolds are well suited for liquid-phase complexation of soft metal ions; however, their binding potential was not extensively studied at the air–water interface, and the effect of thioether topology on metal ion binding mechanisms under various conditions was not considered. Herein, we report...

Supramolecular systems based on transition metal complexes capable of reversible redox isomerization due to intramolecular electron transfer are one of the most interesting objects from the viewpoint of molecular switches’ design. In the present work, a comparative analysis of valence transformation of lanthanide complexes (Sm, Er, Tm and Yb) with...

Achievement of information storage at molecular level remains a pressing task in miniaturization of computing technology. One of the promising approaches for its practical realization is development of nanoscale molecular switching materials including redox‐active systems. The present work demonstrates a concept of expansion of a number of availabl...

Reversible nucleophilic addition to a phthalocyanine core was observed for the first time for the electron-deficient cationic phosphorus(V) complex [PcP(OMe)2]+, whose reaction with KOH afforded a highly distorted nonaromatic adduct bearing an OH group at one of the α-pyrrolic carbon atoms. This adduct was characterized by single-crystal X-ray diff...

Coordination-induced spin crossover (CISCO) in nickel(II) porphyrinates is an intriguing phenomenon that is interesting from both fundamental and practical standpoints. However, in most cases, realization of this effect requires extensive synthetic protocols or extreme concentrations of extra-ligands. Herein we show that CISCO effect can be prompte...

Current research in sandwich phthalocyaninates enjoys increasing interest due to peculiar properties of these compounds, i.e. their intense coloration and ability to change and control it via redox processes. Obviously, such effect found its application in development of electrochromic devices. In the case of commonly studied rare earth element bis...

The reliability of evolutionary reconstructions based on the fossil record critically depends on our knowledge of the factors affecting the fossilization of soft‐bodied organisms. Despite considerable research effort, these factors are still poorly understood. In order to elucidate the main prerequisites for the preservation of soft‐bodied organism...

Herein we report the synthesis and characterization of a series of new dyads – imidazo-fused Ni(II) porphyrinates, containing polycyclic aromatic hydrocarbons (PAH) at the C-2 position of the imidazole ring, including pyrene – 1Pyr, anthracene – 1An, and diphenylanthracene – 1Ph2An. Electronic communication between the tetrapyrrolic macrocycles and...

Reusable dual-channel optical sensors for Hg²⁺ ions were prepared by Langmuir-Schaefer (LS) method from amphiphilic (trans-A2)BC-type porphyrins functionalized at meso-positions of the tetrapyrrolic macrocycle by sterically demanding diethoxyphosphoryl and mesityl groups as well as electron donating RO, RS or RNH substituents (R = n-C8H17). These t...

In the present work, we investigate, by means of in situ UV-Vis reflection-absorption spectroscopy and X-ray reflectivity measurements, the effect of the mercury ion analyte on the supramolecular structure of the dithia-aza-crown-hemicyanine chromoionophore Langmuir monolayers upon their interaction at the air/water interface. It was revealed that...

Designing sensors for toxic compounds such as mercury salts in aqueous solutions still remains one of the most pressing tasks of modern chemical research, since many existing systems do not show enough sensitivity and/or response. In this regard, the opportunities offered by supramolecular approaches can be used to improve both these characteristic...

Cellular membrane is one of the main targets of photodynamic therapy. Its high complexity has led to the study of the efficiency of photosensitizers on artificial lipid systems mimicking membranes. However, the preliminary analysis of this efficiency remains limited due to difficulty of the model construction and/or implementation of the required m...

Thiol- and thioacetate-based functional groups enjoy much attention as anchors for building of self-assembled monolayers (SAM), while SAM formation based on readily accessible benzoyl derivatives remain unexploited. In the present work, we study the SAM-forming ability of a simple octylthiobenzoate and a redox-active metal-free phthalocyanine beari...

New di- and tetrasubstituted thiacalix[4]arenes in cone and 1,3-alternate configurations containing terpyridine and triazole fragments at the lower rim of the macrocycle, as well as model triazole-terpyridine, are synthesized. The structures and purity of the compounds are confirmed by NMR spectroscopy and high-resolution MALDI mass spectrometry. T...

Redox isomerism, that is, the change of a metal cation valence state in organic complexes, can find promising applications in multistable molecular switches for various molecular electronic devices. However, despite a large number of studies devoted to such processes in organic complexes of multivalent lanthanides, redox-isomeric transformations we...

The work presents the results of a study of the negative photochromism and luminescent properties of 1',3'-dihydro-3',3'-dimethyl-6-nitro-1'-octadecyl-[1-benzopyran-2,2'-indole]-8-methyl pyridinium chloride (SP2) in solutions, Langmuir monolayers, and cast films. It has been demonstrated that the introduction of the pyridine substituent into the ch...

In the present work, we demonstrate that transversal conductivity and, consequently, electrochemical activity of ultrathin solid films of two structurally similar octa-butoxy and tetra-crown-ether substituted europium bisphthalocyaninates are quite different. It is shown that presence of the crown moieties allows excellent transfer of charge throug...

New derivatives of 2-(4-vinylchromen-2-ylidene)malononitrile and 2-(2-vinylchromen-4-ylidene)malononitrile were synthesized using the Knoevenagel reaction of 2-(4-methyl-chromen-2-ylidene)malononitrile and 2-(2-methylchromen-4-ylidene)malononitrile, respectively, with the participation of [1-(2-n-butoxyethyl)-2,2,4,7-tetramethyl-1,2,3,4-tetrahydroq...

The dynamic behaviour of a porphyrin dimer, based on covalent linkage of two macrocyclic moieties by a butadiyne connector was studied in thin films by UV-Vis and emission spectroscopies. The degree of π-conjugation through the control of intramolecular motion was investigated without employing extreme conditions such as cryogenic temperatures or h...

Macrocyclic tetrapyrrolic compounds, such as naturally occurring or artificial porphyrins and phthalocyanines, have unique and highly attractive properties for applications in medicine and technology. The interaction of free-base phthalocyanine (H2Pc) and tetraphenylporphyrin (H2TPP) molecules with low-energy (0–15 eV) electrons was studied in vacu...

An ultrathin film, wherein a resonance energy transfer (FRET) from the energy donor monolayer to the analyte sensitive acceptor monolayer is controlled by definable cation binding, was produced, thus proving the feasible concept of non-covalently linked FRET couple based sensors.

It was demonstrated that, in contrast to a solution in an organic solvent, the relaxation of the excited state of a fluorophore moiety proceeds mainly radiationless upon the formation of naphthalimide fluoroionophore complexes with complementary cations in a monolayer on a water surface. Apparently, this is due to the fact that the distribution of...

The efficiency of the Förster resonance energy transfer (FRET) in a monolayer film containing the energy donor and energy acceptor fluorophores is low since the energy transfer process occurs in one plane only. As the number of layers increases to five, the energy transfer efficiency increases due to the interlayer energy transfer occurring in thre...

Europium(III) and terbium(III) complexes with 4-n-octyloxybenzoic acid of the composition LnL3 were synthesized and their luminescent properties were studied. It was established that the luminescence intensity of the TbL3 complex in the visible region is much higher than that of EuL3. Langmuir monolayers of these compounds on the water subphase and...

The results of a study of the photochromic properties of 1´-hexadecyl-3´,3´-dimethyl-6-nitro-1´,3´-dihydrospiro[chromene-2,2´-indole] (SP) are presented. The kinetic characteristics of photophysical processes occurring in acetonitrile solution of SP upon irradiation with UV light and during dark relaxation are determined. It is shown that spiropyra...

Cambrian Lagerstätten host rocks are frequently composed of kaolinite and chlorite in varying amounts; accordingly, our goal was to study the preservation potential of crustaceans in these two clays. We conducted long-term experiments (12–18 months, the longest duration of actualistic taphonomy experiments from published literature) on the decay of...

This study takes a novel approach to the enhancement of receptor properties of thin film sensors based on hemicyanine dyes with dithia-aza-crown- ionophoric moiety. By means of in situ UV-Vis and XRR measurements it was revealed that the introduction of up to 0.25 mmol of Hg2+ under a preliminarily compressed monolayer, formed on pure water does no...

In the multilayer systems where monolayers of donor and acceptor fluorophores of different chemical structure are separated by an inert layer, the dependence of nonradiative energy transfer efficiency on the distance between the planar components of a donor–acceptor couple has a maximum at a finite nonzero thickness of the separating layer.

Corresponding author. Fax: +7 843 273 1872.

Planar supramolecular systems based on Langmuir monolayers of chromoionophores are widely used for sensor applications, and crown ether ionophoric groups are intensively studied. However, almost no attention is devoted to investigation of effect of alkyl moieties onto receptor properties of such systems. In the present work, we carry out a comparat...

The mechanism that guides the formation of exceptionally preserved fossils with soft tissues variously displayed is a paramount challenge to paleontology. The key question for exceptional preservation is the nature of the slowdown of decay and acceleration of soft tissue mineralization. Here we report the experimental formation of subfossils of the...

Lagerstätten, places where soft-bodied organisms became mineralized, provide a substantial bulk of palaeobiological information, but the detailed mechanisms of how soft-tissue preservation takes place remain debatable. An experimental taphonomy approach, which allows for direct study of decay and mineralization, offers a means to study the preserva...

The present work deals with processes of structure-formation and aggregation behavior of hemicyanine chromoionophores in Langmuir monolayers and Langmuir-Blodgett films. It is revealed that the appearance of excimers upon compression of monolayers of these compounds is associated with cation-ionophore group interaction. The key role of the organic...

States of affairs in which informational intermolecular interactions occur in systems with bounded geometry, such as nanoporous adsorbents or ultrathin films of surface active substances (surfactants), are of particular interest. Molecules with conjugated double bonds are characterized by such physical features as heightened formation energy compar...

Herein, we report the first experimental observations on decomposition of organic remains in colloidal solutions of kaolinite. Modeling fossilization in clay colloids is one of the challenging issues for understanding the formation of Lagerstätten, which often occur in fine-grained rocks deposited under catastrophic conditions.

This paper analyzes the prospects of studying optically anisotropic monolayers on a liquid substrate using linearly polarized light. For quantification of the electronic transmission spectra of the studied monolayers on the transparent subphase and Langmuir-Blodgett films transferred onto transparent plates as well, we obtained formulas for optical...

Physico-chemical properties of monolayers of tetra-15-crown-5-phthalocyanine ligand were studied using Langmuir-Blodgett technique and fiber optic spectroscopy. Dependences between concentration of monolayer forming solution and phthalocyanine ligand aggregation degree in monolayer were established. True stable monolayers of tetra-15-crown-5-phthal...

The spectral, electrochemical, and optical properties of Langmuir-Blodgett films (LBFs) and cast films from a solution of new double-decker cerium bis[tetra-(15-crown-5)-phthalocyaninate] (Ce(R4Pc)2) are studied. Based on analysis of compression isotherms and quantum-chemical calculations, schemes of the organization of Ce(R4Pc)2 molecules at diffe...

The spectral and electrochemical properties of Langmuir-Blodgett (LB) films of homoleptic double-decker cerium bis-[tetra-15-crown-5]-phthalocyaninate Ce[R4Pc]2 and its heteroleptic analog [Pc]Ce[R4Pc] were studied. It was shown that during formation of Langmuir monolayers upon contact of both complexes solutions with water subphase the metal cente...

The ability of the triple-decker gadolinium complex with tetra-15-crown-5-phthalocyanine Gd2(R4Pc)3, (R = 15-crown-5) (1) to form monolayers and Langmuir-Blodgett films (LBFs) was studied for the first time. The charge characteristics of molecules of a triple-decker phthalocyaninate in monolayer, as well as their orientation and adhesion to the wat...