- Titanium-Based Tetrakis-2,3-[5,6-di(Substituted)pyrazino]porphyrazine: Synthesis and Characterization
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Tetrapyrazinoporphyrazine (TPysPz) ligands and metal complexes find, generally, application as electronic materials and catalysts. Considering the limited application of Titanium (Ti), we prepared and characterized a family of ligands and Ti-based complexes of tetrakis-2,3-[5,6-di-R8-pyrazino]porphyrazine (R = H, 2-Py, Ph). UV/Vis measurements in different solvents confirm molecular aggregation, which results more pronounced in the presence of 2-pyridil and phenyl substituents on the macrocycle edge. Because of low solubility, solid state NMR was applied for structure characterization. Additional IR and MALDI-TOF were carried out to complete the characterization. Cyclic voltammetry in DMSO/Bu4NBF4 0.1 m unveiled that our Ti complexes can take part in up to five redox events. The first two quasi-reversible reductions involve Ti(IV), whereas the further to or three occur at the expense of the TPysPz macrocycle. To test the applicability of our compounds as catalytic materials, we performed a preliminary cyclic voltammetry investigation in the solid-state, which showed typical peaks of hydrogen redox reactions.
- Assunta Navarra, Maria,D'Acunzo, Francesca,Gentili, Patrizia,Geppi, Marco,Mancone, Carmine,Martini, Francesca,Mazzapioda, Lucia,Nardelli, Francesca,Renzi, Polyssena
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- Selective gas adsorption and unique structural topology of a highly stable guest-free zeolite-type MOF material with N-rich chiral open channels
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A new multifunctional ditopic tetrazolate-based ligand, 2,3-di-1H-tetrazol-5-ylpyrazine (H2dtp) has been designed and synthesized. The solvothermal reaction of this ligand with ZnCl2 gave a robust guest-free three-dimensional zeolite-like chiral metal-organic framework (MOF) complex, [Zn(dtp)], which crystallized in chiral space group P61 and possessed chiral open channels with nitrogen-rich walls and the diameter of approximately 4.1 A. This framework presents a unique uniform etd (8,3) topology, is the first example of its type in MOFs, and exhibits high thermal stability with the decomposition temperature above 380°C and permanent porosity. It is interesting that this material is able to selectively adsorb O2 and CO2 over N2 gas, being a rare example in MOFs. In addition, C2H2 and MeOH adsorption results show that although the framework channel holds nitrogen-rich walls that may provide H-bonding sites, no N...H H-bond effect between the guest molecules and microporous surface was observed.
- Li, Jian-Rong,Tao, Ying,Yu, Qun,Bu, Xian-He,Sakamoto, Hirotoshi,Kitagawa, Susumu
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- Subphthalocyanine azaanalogues – Boron(III) subporphyrazines with fused pyrazine fragments
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Сyclotrimerization of pyrazine-2,3-dicarbonitrile and its phenyl substituted derivative in the presence of BCl3 in p-xylene leads to azaanalogues of subphthalocyanine dye. Non-substituted tripyrazinosubporphyrazine [Pyz3sPABCl] was formed only in trace amounts allowing only limited spectral study in solution. Hexaphenyl substituted derivative [Ph6Pyz3sPABCl] was isolated as chlorboron(III) complex and fully characterized by 1H, 13C, 11B NMR, IR, electronic absorption and emission spectroscopy, cyclovoltammetry and its structure was established by single crystal X-ray diffraction. Pyrazine fused subporphyrazines exhibit strong absorption bands at 300–310 and 530–550 nm. The phenyl substituted derivative [Ph6Pyz3sPABCl] has an additional intense charge transfer band at 390 nm and can be reversibly reduced at ?0.81 V (vs Ag/AgCl in MeCN). The influence of pyrazine rings on the geometrical and electronic structural features and spectral properties of subporphyrazine dye was also studied using DFT and TD DFT methods. Experimental and theoretical results evidence that fusion of pyrazine rings leads to stabilization of the frontier π-molecular orbitals and endows the macrocycle with enhanced electron deficiency. Pyrazine fused subporphyrazines can be considered as perspective dyes intensively absorbing in the 300–600 nm range for applications as n-type materials in organic electronics.
- Stuzhin, Pavel A.,Skvortsov, Ivan A.,Zhabanov, Yuriy A.,Somov, Nikolai V.,Razgonyaev, Oleg V.,Nikitin, Ivan A.,Koifman, Oskar I.
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p. 888 - 897
(2018/11/25)
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- Silica gel an efficient catalyst for one-pot synthesis of pyrazines from ethylenediamine and 1, 2-diketones and their analogs
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A straightforward one-pot synthesis of pyrazines from ethylenediamine and 1, 2-diketones/ α-hydroxy ketone/α-bromo ketone under solvent-free conditions at room temperature is described. This environmentally benign process has the edge on previous methods in respect of workup procedure, ease and cost of reaction, and use and generation of hazardous substances. The catalyst is recovered, characterized, and proved to be recyclable for successive four runs examined with appreciable conversions.
- Chakraborty, Rakesh Ranjan,Singha, Rabindranath,Ghosh, Pranab
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p. 373 - 378
(2018/09/29)
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- Clean and green approach for one-pot synthesis of pyrazines from Eth-ylenediamine and 1,2-diketone or its analogues under neat reaction condition
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Background: Compounds having N-heterocyclic moieties are of huge importance in the field of agrochemical, pharmaceutical, biological, fragrances, etc. Due to a lot of applications associated with pyrazine moieties, their synthesis has always been important for organic chemists. Method: Surfeit synthetic methodologies are documented in literature. Most of the methodologies used expensive solvents, harmful metal catalyst and all suffer from rigorous work-up procedures. An efficient, environmentally benign methodology, needs to be developed. We mixed ethylenediamine (2mmol) with 1, 2-diketone(1mmol), later, α-hydroxy ketone and α-bromo ketone on magnetic stirrer at room temperature under neat reaction condition for 5 to 10 hrs. Results: After purification by column chromatography using silica gel(60-120 mesh) and pet-ether, et-hylacetate mixture as eluent, we achieved pyrazine derivatives from moderate to high yield. Conclusio n: Efficient and clean procedure for one-pot preparation of pyrazines from ethylenediamine and 1, 2-diketones or with α-hydroxy ketone or with α-bromo ketone has been carried out under neat reaction condition at room temperature. Environmentally benign process furnishing moderate to excellent yields of the product and simple work-up giving pure products are special features of this reaction.
- Ghosh, Pranab,Chakraborty, Rakesh Ranjan
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p. 566 - 570
(2017/09/29)
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- Facile synthesis of hydrazine derivatives of 5H-pyrrolo[3,4-b]pyrazine and 1H-pyrrolo[3,4-b]quinoxaline
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A convenient and efficient route for the chemoselective synthesis of carbohydrazide, arenesulfonylhydrazide, and thiosemicarbazone derivatives of 5H-pyrrolo[3,4-b]pyrazine and 1H-pyrrolo[3,4-b]quinoxaline from the corresponding dinitriles and substituted hydrazines was elaborated. The synthesis of starting pyrazine-2,3-dicarbonitrile was sufficiently improved by using concentrated HCl as a catalyst. Georg Thieme Verlag Stuttgart . New York.
- Hordiyenko, Olga V.,Rudenko, Igor V.,Zamkova, Irina A.,Denisenko, Oleksandr V.,Biitseva, Angelina V.,Arrault, Axelle,Tolmachev, Andrei A.
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p. 3375 - 3382
(2014/01/06)
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- Substituent Effects on Photochemical Hydrogen Abstraction in 2-Acylpyridines, 2-Acylpyrazines, and 4-Acylpyrimidines
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Stern-Volmer quenching of the photochemistry of 1c indicates that N- and O-abstraction (eqs 1 and 2, respectively) are quenched at different rates (Figure 1).For quenching of 2c kqτ is 157 M-1 and for 3c, 64 M-1.When 1c is sensitized with triplet sensitizers of increasing ET,N-abstraction increases (Table 1).These data indicate that N- and O-abstraction in 1c take place from distiguishable triplet states.Survey of Φp's of ring-substituted ketones 1b-d, 6d, 7a,b,d, 8b, 9b,d, 10b, and 11d demonstartes the effect of substitution on the competition between N- and O-abstraction (Table 2).For methyl- and dicyano-substituted ketones, the results can be understood simply in terms of shifts in ET of the n?* and ??* states of the heterocycle.The photochemistry of all these ketones requires consideration of interactions among three triplet states.
- Rao, C. Janakiram,Agosta, William C.
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p. 2125 - 2131
(2007/10/02)
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- Hydrogen Cyanide Chemistry. 9. Cycloaddition Reactions and Nitrenium Ion Type Reactivity of Diiminosuccinonitrile
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Cycloaddition reactions of diiminosuccinonitrile (DISN) with nucleophilic olefins yield a variety of products including cycloadducts and aziridines.All of the products derived from 1,3-dienes, styrene, para-substituted styrenes, cycloheptatriene, norbornene, and norbornadiene can be accounted for by rearrangements of a common intermediate, zwitterionic aziridinium ion.We introduce the concept of reverse polarization and propose that DISN is a latent nitrenium ion source (isoelectronic with carbenes) and that reverse polarization of one of the >C=N bonds of DISNis responsible for the observed reactions.Comments are made on reverse polarization of other >C=X bonds, and facile 1,1-cycloreversion of aziridines is also reported.
- Fukunaga, Tadamichi,Begland, Robert W.
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p. 813 - 821
(2007/10/02)
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