Alexander G. Martynov

Electrochemical and Spectroelectrochemical Studies of Diphosphorylated Metalloporphyrins. Generation of a Phlorin Anion Product

Two series of diphosphoryl-substituted porphyrins were synthesized and characterized by electrochemistry and spectroelectrochemistry in nonaqueous media containing 0.1 M tetra-n-butylammonium perchlorate (TBAP). The investigated compounds are 5,15-bis(diethoxyphosphoryl)-10,20-diphenylporphyrins (Ph)2(P(O)(OEt)2)2PorM and 5,15-bis(diethoxyphosphoryl)-10,20-di(para-carbomethoxyphenyl)porphyrins (PhCOOMe)2(P(O)(OEt)2)2PorM where M = 2H, Co(II), Ni(II), Cu(II), Zn(II), Cd(II), or Pd(II). The free-base and five metalated porphyrins with nonredox active centers undergo two ring-centered oxidations and two ring-centered reductions, the latter of which is followed by a chemical reaction of the porphyrin dianion to give an anionic phlorin product. The phlorin anion is electroactive and can be reoxidized by two electrons to give back the starting porphyrin, or it can be reversibly reduced by one electron at more negative potentials to give a phlorin dianion. The chemical conversion of the porphyrin dianion to a phlorin anion proceeds at a rate that varies with the nature of the central metal ion and the solvent. This rate is slowest in the basic solvent pyridine as compared to CH2Cl2 and PhCN, giving further evidence for the involvement of protons in the chemical reaction leading to phlorin formation. Calculations of the electronic structure were performed on the Ni(II) porphyrin dianion, and the most favorable atoms for electrophilic attack were determined to be the two phosphorylated carbon atoms. Phlorin formation was not observed after the two-electron reduction of the cobalt porphyrins due to the different oxidation state assignment of the doubly reduced species, a Co(I) π anion radical in one case and an M(II) dianion for all of the other derivatives. Each redox reaction was monitored by thin-layer UV-visible spectroelectrochemistry, and an overall mechanism for each electron transfer is proposed on the basis of these data.

Crown-substituted phthalocyanines—components of molecular ionoelectronic materials and devices

This review summarizes the synthetic approaches towards oxa-crown-substituted phthalocyanines (CRPc’s) including various metal complexes of s-, p-, d-, and f-elements. The template cyclotetramerization of phthalonitriles and direct metalation pathways for synthesis of target compounds are discussed and compared. It is demonstrated that obtained results have contributed to coordination, supramolecular, and materials chemistry of phthalocyanines in general. An analysis of the results published to date reveals the challenges of these compounds for their use in high-tech applications.

A Molecular Chameleon: Reversible pH- and Cation-Induced Control of the Optical Properties of Phthalocyanine-Based Complexes in the Visible and Near-Infrared Spectral Ranges

A series of novel nonperipherally substituted tetra-15-crown-5-dibutoxyoxanthrenocyanines (H2, Mg, Zn), acting as chameleons with the unique properties of switchable absorption and emission in the near-infrared (NIR) spectral range have been synthesized and characterized by X-ray diffraction. The attachment of 15-crown-5-α-dibutoxyoxanthreno moieties to phthalocyanine is responsible for the high solubility of the resulting molecules and the red shift of the Q band to the NIR region and offers a unique possibility for postsynthetic modification of the optical properties of the molecules. Both aggregation of phthalocyanine and its participation in an acid-base equilibrium strongly alter their optical properties. For example, the absorption of complexes can be reversibly tuned from 686 up to 1028 nm because of the cation-induced formation of supramolecular dimers or subsequent protonation of meso-N atoms orf macrocycle, in contrast to peripherally substituted tetra-15-crown-5-phthalocyanines without oxanthrene moieties. The reversibility of these processes can be controlled by the addition of [2.2.2]cryptand or amines. All investigated compounds exhibit fluorescence with moderate quantum yield, which can also be switched between the ON and OFF states by the action of similar agents.

The crucial role of self-assembly in nonlinear optical properties of polymeric composites based on crown-substituted ruthenium phthalocyaninate†

Ruthenium(II) tetra-15-crown-5-phthalocyaninate with axially coordinated molecules of pyrazine [(15C5)4Pc]Ru(pyz)2 (1) was synthesized from a carbonyl complex [(15C5)4Pc]Ru(CO)(MeOH) (2), and the structure of the solvate complex (1)·6CHCl3 was revealed using the single crystal X-ray diffraction method. Analysis of the crystal packing showed that the weak intermolecular interactions, such as CH⋯π, CH⋯N, CH⋯O and CH⋯Cl, played an essential role in the formation of stable assemblies and their organization within the crystals. The interplay between the intramolecular axial coordinated pyrazine contacts and the weak intermolecular interactions of solvate molecules with crown-ether fragments provided the basis for rationalizing the observed self-assembly of molecules in solutions of tetrachloroethane and polymeric composites with polyvinylcarbazole. The self-assembly was investigated using UV-Vis spectroscopy, dynamic light scattering measurements, atomic force microscopy and transmission electron microscopy techniques. The formation of nanoparticles of complex (1) from a tetrachloroethane solution after three cycles of heating to 70 °C/cooling to 5 °C and two days storage was proved. Thin films (7 μm) of polymeric composites with polyvinylcarbazole prepared from a solution containing nanoparticles exhibited a nonlinear optical response measured by the Z-scan technique with application of femtosecond (1030 nm) and nanosecond (1064 nm) pulse lasers. The measured third-order susceptibility (χ(3)) of the polyvinylcarbazole composite with 4 wt% of complex (1) was equal to 1.94 × 10−10 esu, while the same composite prepared without the previously described special treatment had zero susceptibility. This result proves the essential role of self-assembly in future development of nonlinear optical materials.

Functional analysis of C1 family cysteine peptidases in the larval gut of Тenebrio molitor and Tribolium castaneum.

BackgroundLarvae of the tenebrionids Tenebrio molitor and Tribolium castaneum have highly compartmentalized guts, with primarily cysteine peptidases in the acidic anterior midgut that contribute to the early stages of protein digestion.ResultsHigh throughput sequencing was used to quantify and characterize transcripts encoding cysteine peptidases from the C1 papain family in the gut of tenebrionid larvae. For T. castaneum, 25 genes and one questionable pseudogene encoding cysteine peptidases were identified, including 11 cathepsin L or L-like, 11 cathepsin B or B-like, and one each F, K, and O. The majority of transcript expression was from two cathepsin L genes on chromosome 10 (LOC659441 and LOC659502). For cathepsin B, the major expression was from genes on chromosome 3 (LOC663145 and LOC663117). Some transcripts were expressed at lower levels or not at all in the larval gut, including cathepsins F, K, and O. For T. molitor, there were 29 predicted cysteine peptidase genes, including 14 cathepsin L or L-like, 13 cathepsin B or B-like, and one each cathepsin O and F. One cathepsin L and one cathepsin B were also highly expressed, orthologous to those in T. castaneum. Peptidases lacking conservation in active site residues were identified in both insects, and sequence analysis of orthologs indicated that changes in these residues occurred prior to evolutionary divergence. Sequences from both insects have a high degree of variability in the substrate binding regions, consistent with the ability of these enzymes to degrade a variety of cereal seed storage proteins and inhibitors. Predicted cathepsin B peptidases from both insects included some with a shortened occluding loop without active site residues in the middle, apparently lacking exopeptidase activity and unique to tenebrionid insects. Docking of specific substrates with models of T. molitor cysteine peptidases indicated that some insect cathepsins B and L bind substrates with affinities similar to human cathepsin L, while others do not and have presumably different substrate specificity.ConclusionsThese studies have refined our model of protein digestion in the larval gut of tenebrionid insects, and suggest genes that may be targeted by inhibitors or RNA interference for the control of cereal pests in storage areas.

Synthesis and structure of heteroleptic triple-decker neodymium, europium, holmium, erbium, and ytterbium crown phthalocyaninates

Two series of heteroleptic crown-substituted tris(phthalocyaninate) complexes (Pc)Ln[(15C5)4Pc]Ln(Pc) and [(15C5)4Pc]Ln[(15C5)4Pc]Ln(Pc), where 15C5 is 15-crown-5, (Pc2−) is the phthalocyaninate dianion, Ln = Nd, Eu, Ho, Er, and Yb, were prepared by the reaction of tetra-15-crown-5-phthalocyanine H2[(15C5)4Pc] with the corresponding lanthanide acetylacetonates and lanthanum bis(phthalocyaninate) La(Pc)2, which was used as a phthalocyaninate dianion donor. The composition and structure of the synthesized complexes were confirmed by MALDI TOF mass spectrometry, UV-Vis absorption spectroscopy, and 1H NMR. Complete assignment of the proton resonance signals of the paramagnetic lanthanide complexes was based on analysis of lanthanide-induced shifts.

Monoclonal antibodies to angiotensin-converting enzyme: a powerful tool for lung and vessel studies.

We obtained a series (12 clones) of hybridomas, which produce monoclonal antibodies (Mab) to 5 different epitopes of the angiotensin-converting enzyme (ACE) molecule. These antibodies may be used to (1) map antigenic structure of ACE, including the study of immunologic heterogeneity of ACE from different organs and tissues; (2) study the immunohistochemical distribution of ACE in human tissues, including the diagnosis of sarcoidosis; (3) develop an ACE immunoassay, and (4) prepare an immunosorbent for large-scale ACE isolation and for ACE-apheresis. One of the antibodies, 9B9, when injected into the circulation of rat and monkey, accumulated with high specificity in the lungs as compared with either normal mouse IgG or other organs and blood. The highly specific and nontoxic accumulation of Mab 9B9 suggests that it also may be used for gamma scintigraphy visualization of the pulmonary vascular bed, detection of lung injury and as a vector for targeted drug delivery to the lung.

Bacillus thuringiensis Cry3Aa protoxin intoxication of Tenebrio molitor induces widespread changes in the expression of serine peptidase transcripts

The yellow mealworm, Tenebrio molitor, is a pest of stored grain products and is sensitive to the Bacillus thuringiensis (Bt) Cry3Aa toxin. As digestive peptidases are a determining factor in Cry toxicity and resistance, we evaluated the expression of peptidase transcripts in the midgut of T. molitor larvae fed either a control or Cry3Aa protoxin diet for 24 h (RNA-Seq), or in larvae exposed to the protoxin for 6, 12, or 24 h (microarrays). Cysteine peptidase transcripts (9) were similar to cathepsins B, L, and K, and their expression did not vary more than 2.5-fold in control and Cry3Aa-treated larvae. Serine peptidase transcripts (48) included trypsin, chymotrypsin and chymotrypsin-like, elastase 1-like, and unclassified serine peptidases, as well as homologs lacking functional amino acids. Highly expressed trypsin and chymotrypsin transcripts were severely repressed, and most serine peptidase transcripts were expressed 2- to 15-fold lower in Cry3Aa-treated larvae. Many serine peptidase and homolog transcripts were found only in control larvae. However, expression of a few serine peptidase transcripts was increased or found only in Cry3Aa-treated larvae. Therefore, Bt intoxication significantly impacted the expression of serine peptidases, potentially important in protoxin processing, while the insect maintained the production of critical digestive cysteine peptidases.

A model species for agricultural pest genomics: The genome of the Colorado potato beetle, Leptinotarsa decemlineata (Coleoptera: Chrysomelidae)

The Colorado potato beetle is one of the most challenging agricultural pests to manage. It has shown a spectacular ability to adapt to a variety of solanaceaeous plants and variable climates during its global invasion, and, notably, to rapidly evolve insecticide resistance. To examine evidence of rapid evolutionary change, and to understand the genetic basis of herbivory and insecticide resistance, we tested for structural and functional genomic changes relative to other arthropod species using genome sequencing, transcriptomics, and community annotation. Two factors that might facilitate rapid evolutionary change include transposable elements, which comprise at least 17% of the genome and are rapidly evolving compared to other Coleoptera, and high levels of nucleotide diversity in rapidly growing pest populations. Adaptations to plant feeding are evident in gene expansions and differential expression of digestive enzymes in gut tissues, as well as expansions of gustatory receptors for bitter tasting. Surprisingly, the suite of genes involved in insecticide resistance is similar to other beetles. Finally, duplications in the RNAi pathway might explain why Leptinotarsa decemlineata has high sensitivity to dsRNA. The L. decemlineata genome provides opportunities to investigate a broad range of phenotypes and to develop sustainable methods to control this widely successful pest.

Improvement of nonlinear optical properties of phthalocyanine bearing diethyleneglycole chains: Influence of symmetry lowering vs. heavy atom effect

This paper reports the successful synthesis of the low symmetry phthalocyanines: metal-free 2,3-bis[2′-(2′′-hydroxyethoxy)ethoxy]-9,10,16,17,23,24-hexa-n-butoxyphthalocyanine 1H2 and its zinc complex 1Zn along with their nonlinear optical (NLO) behavior in solution and in thin films. 1H NMR investigations evidenced of higher dissymmetry of electronic density in 1H2 in comparison with 1Zn. This dissymmetry is responsible for unusually higher values of Im[χ(3)]/α, βeff, and γ for 1H2in contrast to 1Zn, where the notable effect of heavy-metal enhancement of ISC was expected. Both compounds showed Im[χ(3)]/α values of the order of 10−11 in chloroform which are higher in comparison to the symmetrical octabutoxyphthalocyanine H2[(BuO)8Pc]. NLO properties of 1H2 were improved via its incorporation into polycarbonate polymeric matrix together with CdSe@CdS-TOPO quantum dots. In such composite the value of Im[χ(3)]/α was almost three times higher in comparison with 1H2 solution in chloroform. The obtained composites are expected to be perspective components of optical materials, capable of protection against strong light irradiation.