Ilya S. Grigoryev

Novel metal-template assembled highly-functionalized cyanoporphyrazine ytterbium and vanadium complexes for potential photonic and optoelectronic applications

A novel facile synthetic route to the metal-template assembly of a tetrapyrrollic framework from tetracyanoethylene (TCNE) and tricyanovinylbenzene (TCNVB) structural units through reaction of TCNE and TCNVB with metal π-sandwich complexes has been developed. The reactions occur under extremely mild conditions, the porphyrazine macrocycles being assembled in high yield from TCNE and TCNVB building-blocks by VO2+ or Yb3+-template synthesis. The redox behaviour of the novel complexes has been investigated. The vanadyl octacyanoporphyrazine complex was found to be a rare example of a highly-absorbing dye combining significant electron-acceptor properties with a band gap unusually narrow for an organic semiconductor (ca. 1.1 eV). The preparation is described of a novel highly emissive ytterbium complex with a proposed unusual structure obtained by reaction of TCNVB with bis(indenyl)ytterbium(II) in THF. The analytical, spectral and electrochemical investigations of the obtained ytterbium complex indicate it to be a binuclear adduct with Yb(TCNVB)3 species in which a single doubly-reduced TCNVB molecule bridges two Yb3+ cations. The formation of a disordered polynuclear coordination polymer network including a macrocyclic structure and metal cations bridged through the nitrile nitrogen atoms is proposed. The complex is readily soluble and is compatible with a variety of polymeric matrices giving doped polymeric glasses and films which are highly luminescent in the biologically relevant optical window covering the visible and near-infrared (NIR) range (640–1000 nm). In addition, doped polymeric glasses and films highly emissive at the telecommunication wavelength (1540 nm), including a composition consisting of the novel ytterbium complex and an equimolar ratio of the novel ytterbium complex and a per se non-luminescent erbium chelate, have been obtained. The complex is found to be an extraordinarily strong sensitizer of NIR Er3+ emission.

Chromium-containing organometallic nanomaterials for non-linear optics

Novel non-linear optical polymeric film-producing nanocomposites based on bis(arene)chromium complexes incorporated into a CN-containing matrix have been developed. Polymeric nanocomposite precursors were prepared by the reaction of Cr(EtnC6H6−n)2 (n = 1,2,3) with CN-containing vinyl monomers (acrylonitrile, crotononitrile or ethyl 2-cyanopropenoate). Extraordinarily high third-order non-linear optical susceptibilities of the ultra-fast electronic type have been demonstrated at various wavelengths for polymer films prepared from these composites by using the Z-scan technique and the spectrally-resolved two-beam coupling method. A notable electro-optical response of the composite with an essential contribution of orientational effects was established. The electron-diffraction pattern in films and the presence of a non-zero electro-optical coefficient in the absence of an external poling field indicate the formation of self-organized structures. In CrPAN and [CrPAN]+TCNE−, a single Cr–C distance was found in the EXAFS data refinement, showing that the arene rings are parallel and symmetric as in bis(benzene)chromium. The Cr–C distances in these two materials are very similar to the 2.13 A in bis(benzene)chromium. In [CrPAN]+OH−, more than one metal–carbon distance was resolved, showing either that the two arene rings are at different distances from the metal, or that they are tilted rather than parallel.

New porphyrazine macrocycles with high viscosity-sensitive fluorescence parameters

New tetraaryltetracyanoporphyrazines have been obtained in the form of metal complexes and free bases via template assembly of a variety of aryltricyanoethylenes as structural units of the macrocycle, and photophysical properties of the products have been studied. The unique high sensitivity of the fluorescent properties to viscosity has been demonstrated. This property opens the possibility of application of the said compounds as sensors of local viscosity. The prepared macrocycles exhibit significant photocytotoxicity, and can be thus used as sensitizers of photodynamic therapy.

Efficient Luminescent Solar Concentrators Based on Defectless Organic Glasses Containing Novel Ytterbium Cyanoporphyrazine Complex

A photocurable polymeric luminescent composition doped by a new ytterbium tetra(4-fluorophenyl)tetracyanoporphyrazine complex capable of efficiently absorbing and reemitting light in a wide spectral range is developed. Defect-free organic glasses obtained with the use of this composition were applied as waveguides in the creation of laboratory models of a luminescent solar concentrator. Tests results of the created models showed the possibility of creating a stationary solar energy concentrator for photovoltaic cells (PVCs) which is at least as efficient as the best kinds of similar devices previously found worldwide.

Metal template assembly of highly functionalized octacyanoporphyrazine framework from TCNE structural units.

A new route to the octacyanoporphyrazine framework based on the interaction of metal sandwich pi-complexes with TCNE has been developed.

Chromium-containing Organometallic Self-organized Materials for Nanophotonics

Novel non-linear optical polymeric film-producing nanocomposites based on bis(arene)chromium complexes incorporated into CN-containing matrices have been developed. Measurements by the spectrally resolved two-beam coupling method with a femtosecond range of pulse widths (central wavelength 795-800 nm) confirmed that the test composites exhibited a significant cubic nonlinear optical susceptibility of the ultra-fast electronic type. An open aperture Z-scan of the polymer film at 1550 nm showed a value of 9 x 10-19 cm3 W-2 for the three- photon absorption coefficient. The electro-optical measurements of the polymer composite showed a high electro-optical response (r33.n3 = 4.245 pm V-1 at modulation frequency 210 Hz and poling DC voltage 2.16 V). A significant enhancement of the signals with a decrease in modulation frequency was observed consistent with an essential contribution of orientation effects to the electro- optical response. The measurements in the absence of external electrical fields showed a natural anisotropy resulting from self- organization taking place during the film formation process as confirmed by electron diffraction studies. A single Cr-C distance was found in the EXAFS data refinement, showing that the arene rings are parallel and symmetric as in bis(benzene)chromium.

In vivo multimodal tumor imaging and photodynamic therapy with novel theranostic agents based on the porphyrazine framework-chelated gadolinium (III) cation

BACKGROUND A promising strategy for cancer diagnosis and therapy is the development of an agent for multimodal imaging and treatment. In the present paper we report on two novel multifunctional agents prepared on the porphyrazine pigment platform using a gadolinium (III) cation chelated by red-fluorescent tetrapyrrole macrocycles (GdPz1 and GdPz2). METHODS Spectral and magnetic properties of the compounds were analyzed. Monitoring of GdPz1 and GdPz2 accumulation in the murine colon carcinoma CT26 was performed in vivo using fluorescence imaging and MRI. The photobleaching of GdPz1 or GdPz2 and tumor growth rate after photodynamic therapy (PDT) were assessed. RESULTS GdPz1 and GdPz2 demonstrated the selective accumulation in tumor that was indicated by higher fluorescence intensity in the tumor area in comparison with the normal tissues. The results of MRI in vivo showed that GdPz1 or GdPz2 provided significant contrast enhancement of the tumor in T1 MR images. PDT with GdPz2 resulted in ~20% decrease in fluorescence intensity of the compound and the inhibition of tumor growth. CONCLUSIONS We assessed the efficiency of two innovative Gd(III) cation-porphyrazine chelates as bimodal MR and fluorescent probes and photosensitizers for PDT and showed their potentials for tumor diagnostics and treatment. GENERAL SIGNIFICANCE Water-soluble structures simple in preparation and administration into the body represent special interest for theranostics of tumors. Novel porphyrazine macrocycles chelating a central gadolinium cation demonstrated a good prospect as effective multimodal agents, representing a new approach to MRI and fluorescence imaging guided PDT.

Novel tetraaryltetracyanoporphyrazine vanadyl complexes with enhanced electron-withdrawing properties

Porphyrazines are the closest chemical analogues of porphyrins in which the meso carbon atoms are replaced by nitrogen atoms, and they exhibit all of the most typical and practically valuable physicochemical properties of macroheterocyclic compounds. For example, these are exceptionally high light absorption coefficients, which are often combined with lumines cence properties over a broad range of wavelengths including the spectral window of relative transparency of the biological tissue. Among specific features of porphyrazines, one can consider their enhanced sta bility against oxidation as compared with porphyrins. Therefore, porphyrazines with electron withdrawing properties can be used as oxidation catalysts, as well as for the design of photovoltaic devices [5, 6]. Note that one of the causes for the insufficiently wide practical application of porphyrazines as compared with their structural analogs, porphyrins and phthalocyanines, is the absence of convenient methods for synthesis. Pre viously, we proposed a new synthetic approach to the macroheterocyclic structure by the reaction of sand wich vanadium and ytterbium complexes with tetracy anoethylene and tricyanovinylbenzene; octacyanopo rphyrazine vanadyl and ytterbium complexes were thus prepared for the first time [7, 8]. The template assembly of the porphyrazine structure from tetracya noethylene molecules as structural units was per formed in high yields under mild conditions on vanadyl and ytterbium cations.

Novel highly emissive tetracyanotetraphenylporphyrazine ytterbium complex for optoelectronic and biophotonic applications

The preparation is described of a novel highly emissive ytterbium complex with a proposed unusual structure obtained by reaction of tricyanovinylbenzene (TCNVB) with bis(indenyl)ytterbium(II) in THF. The reaction occurs under extremely mild conditions, the tetraphenyltetracyanoporphyrazine macrocycle being assembled in high yield from TCNVB building-blocks by Yb3+-template synthesis. The analytical, spectral and electrochemical investigations of the obtained ytterbium complex indicate its existence in the form of a binuclear adduct with Yb(TCNVB)3 species in which a one doubly reduced TCNVB molecule bridges two Yb3+ cations. The formation of a disordered polynuclear coordination polymer network including a macrocyclic structure and metal cations bridged through the nitrile nitrogen atoms is proposed. The complex is readily soluble and is compatible with a variety of polymeric matrices giving doped polymeric glasses and films which are highly luminescent in the biologically relevant optical window covering the visible and near infrared range (640-1000 nm). In addition, doped polymeric glasses and films highly emissive at the telecommunication wavelength (1540 nm) including the novel ytterbium complex and originally not luminescent erbium chelate in an equimolar ratio have been obtained. The compound is found to be an extraordinarily strong sensitizer of near-IR Er3+ emission. Use of the Yb complex as a fluorescent marker for biomedical in vitro investigations has been demonstrated.