Toward carboxylate group functionalized A4, A2B2, A3B oxaporphyrins and zinc complex of oxaporphyrins

Metal Complexes of Porphyrinoids Containing Nonpyrrolic Heterocycles

The replacement of one or more pyrrolic building block(s) of a porphyrin by a nonpyrrolic heterocycle leads to the formation of so-called pyrrole-modified porphyrins (PMPs), porphyrinoids of broad structural variability. The wide range of coordination environments (type, number, charge, and architecture of the donor atoms) that the pyrrole-modified frameworks provide to the central metal ions, the frequent presence of donor atoms at their periphery, and their often observed nonplanarity or conformational flexibility distinguish the complexes of the PMPs clearly from those of the traditional square-planar, dianionic, N₄-coordinating (hydro)porphyrins. Their different coordination properties suggest their utilization in areas beyond which regular metalloporphyrins are suitable. Following a general introduction to the synthetic methodologies available to generate pyrrole-modified porphyrins, their general structure, history, coordination chemistry, and optical properties, this Review highlights the chemical, electronic (optical), and structural differences of specific classes of metalloporphyrinoids containing nonpyrrolic heterocycles. The focus is on macrocycles with similar "tetrapyrrolic" architectures as porphyrins, thusly excluding the majority of expanded porphyrins. We highlight the relevance and application of these metal complexes in biological and technical fields as chemosensors, catalysts, photochemotherapeutics, or imaging agents. This Review provides an introduction to the field of metallo-PMPs as well as a comprehensive snapshot of the current state of the art of their synthesis, structures, and properties. It also aims to provide encouragement for the further study of these intriguing and structurally versatile metalloporphyrinoids.

Selective Functionalization of Achmatowicz Rearrangement Products by Reactions with Potassium Organotrifluoroborates under Transition-Metal-Free Conditions

The repertoire of synthetic transformations of the products of the Achmatowicz rearrangement has been expanded by exploring their reactivity with potassium organotrifluoroborates in the absence of transition metals. Depending on the reaction conditions and the substitution pattern of the starting material, the reaction may lead to the stereoselective synthesis of dihydropyranones (2,6- trans), tetrahydropyranones (2,3- cis-2,6- cis) or functionalized 1,4-dicarbonyl compounds. The method has also been adapted for the one-pot synthesis of functionalized pyrroles.

Rational enhancement of the energy barrier of bis(tetrapyrrole) dysprosium SMMs via replacing atom of porphyrin core

With the coordination geometry of Dy^III being relatively fixed, oxygen and sulfur atoms were used to replace one porphyrin pyrrole nitrogen atom of sandwich complex [(Bu)₄N][Dy^III(Pc)(TBPP)] [Pc = dianion of phthalocyanine, TBPP = 5,10,15,20-tetrakis[(4-tert-butyl)phenyl]porphyrin]. The energy barrier of the compounds was enhanced three times, with the order of Dy^III(Pc)(STBPP) > Dy^III(Pc)(OTBPP) > [(Bu)₄N][Dy^III(Pc)(TBPP)] [STBPP = monoanion of 5,10,15,20-(4-tert-butyl)phenyl-21-thiaporphyrin, OTBPP = monoanion of 5,10,15,20-(4-tert-butyl)phenyl-21-oxaporphyrin]. Theoretical calculations offer reasonable explanations of such a significant enhancement. The energy barrier of 194 K for Dy^III(Pc)(STBPP) represents the highest one among all the bis(tetrapyrrole) dysprosium SMMs, providing a strategy to rationally enhance the anisotropy and energy barrier via atom replacement.

Bio-Based Bisfuran: Synthesis, Crystal Structure and Low Molecular Weight Amorphous Polyester

Discovery of renewable monomer feedstocks for fabrication of polymeric demand is critical in achieving sustainable materials. In the present work we have synthesized bisfuran diol (BFD) monomer from furfural, over four steps. BFD was examined via X-ray crystallography to understand the molecular arrangement in space, hydrogen bonding and packing of the molecules. This data was further used to compare BFD with structurally related Bisphenol A (BPA), and its known derivatives to predict the potential estrogenic or anti-estrogenic activities in BFD. Further, BFD was reacted with succinic acid to generate polyester material, bisfuran polyester (BFPE-1). MALDI characterization of BFPE-1 indicates low molecular weight polyester and thermal analysis reveals amorphous nature of the material.

Rhenium(I) tricarbonyl complex of 5,20-bis(p-tolyl)-10,15-bis(p-methoxyphenyl)-21-selenaporphyrin: first X-ray structural characterization of metal complex of 21-selenaporphyrin

Synthesis and first structural characterization of hexa coordinated rhenium(I) tricarbonyl complex of 5,20-bis(p-tolyl)-10,15-bis(p-methoxyphenyl)-21-selenaporphyrin 3 are described. The Re(I) complex of 21-selenaporphyrin 3 was synthesized by treating free base 21-selenaporphyrin in 1,2-dichlorobenzene with Re(CO)5Cl at reflux for 7 h and analyzed using mass, NMR, FT-IR, UV-vis and electrochemical techniques. The first structure of metal complex of 21-selenaporphyrin was determined by X-ray single crystal analysis. The crystal structure revealed that the Re(CO)3 coordinates to two of the three inner nitrogens and one selenium to produce compound 3. The selenophene ring bent towards the Re(I) ion and the selenium is displaced by 0.41 Å from the mean plane of 24-atoms to coordinate with Re(I) ion in η(1)-fashion. The 21-selenaporphyrin is distorted in compound 3 compared to free base 21-selenaporphyrin. (1)H and (13)C NMR studies indicated that compound 3 exhibits fluxional behaviour in coordination mode of binding in solution. The compound 3 is highly stable and does not undergo decomplexation under acidic conditions. The absorption spectra showed three broad Q-bands and splitted Soret band and electrochemical studies indicated that compound 3 is stable under redox conditions.