148832-75-1Relevant academic research and scientific papers
New macrocyclic polyamines of 3,5-disubstituted 1H-pyrazole. A 13C NMR study of deprotonation and formation of Zn2+ dinuclear complexes
Kumar,Aran,Navarro
, p. 3159 - 3162 (1993)
Dipodal (2+2) condensation of 3,5-(1H-pyrazole)dicarbaldehyde (3) with 1,5-diamino-3-oxapentane (4) and diethylenetriamine (5) followed by hydrogenation of the resulting Schiff bases (6 and 8), affords two new 26 membered polyaza macrocycles of 1H-pyrazole (7 and 9). The deprotonation of both crowns in basic medium as well as the formation of dinuclear Zn2+ complexes (7b and 9b) from the dipyrazolate salts 7a and 9a have been studied by 13C NMR.
Efficient photochemical water oxidation by a dinuclear molecular ruthenium complex
Laine, Tanja M.,K?rk?s, Markus D.,Liao, Rong-Zhen,A?kermark, Torbj?rn,Lee, Bao-Lin,Karlsson, Erik A.,Siegbahn, Per E. M.,A?kermark, Bj?rn
, p. 1862 - 1865 (2015/01/30)
Herein is described the preparation of a dinuclear molecular Ru catalyst for H2O oxidation. The prepared catalyst mediates the photochemical oxidation of H2O with an efficiency comparable to state-of-the-art catalysts.
Experimental and theoretical investigation of the spectroscopic and electronic properties of pyrazolyl ligands
Adeniyi, Adebayo A.,Ajibade, Peter A.
, p. 831 - 845 (2014/07/22)
The electronic and spectroscopic properties of seven pyrazole derivatives are presented in order to give a clear understanding of their distinguishing features. Four out of the seven ligands are synthesised and are also characterised experimentally. A very high correlation was observed between the experimental and the theoretical IR, 1H NMR and 13C NMR, which help in the characterisation of the ligands. The excitation properties computed using the TDDFT shows that most of experimentally observed absorptions of the ligands are predominantly form either the HOMO or HOMO-1 to LUMO or LUMO+1. The characteristic features of the *N atoms (i.e. metal available coordinating centre) shows that the carboxylic unit may possibly decrease the metal affinity of the pyrazole unit while the pyridine unit will increase the affinity. The conductivity properties of the seven ligands are found to be in the order of bdmpzpy > bpzpy > bphpza > bdcpzpy > phpz > dcpz. The J-coupling of *NN can give an insight into the variation in their bond distance, bond stretch and bond strength in the ligands. Also the atomic properties of the *N atoms and their *NN bonds can help in the molecular characterisation, differentiation and in prediction of the non-linear optical properties of the ligands as conductive materials.
Synthesis and Protonation Behavior of 26-Membered Oxaaza and Polyaza Macrocycles Containing Two Heteroaromatic Units of 3,5-Disubstituted Pyrazole or 1-Benzylpyrazole. A Potentiometric and 1H and 13C NMR Study
Aran, Vicente J.,Kumar, Manoj,Molina, Jose,Lamarque, Laurent,Navarro, Pilar,Garcia-Espana, Enrique,Ramirez, Jose A.,Luis, Santiago V.,Escuder, Beatriz
, p. 6135 - 6146 (2007/10/03)
The synthesis and acid-base behavior of two series of 26-membered dioxatetraamine and hexaamine heterocyclophanes containing two nuclei of either pyrazole (4a and 6a) or 1-benzylpyrazole (4b and 6b), respectively, are reported. Dipodal (2 + 2) condensations of 3,5-pyrazoledicarbaldehyde 2a or its 1-benzyl derivative 2b with 1,5-diamino-3-oxapentane afford in both cases the stable Schiff bases 3a,b in 90% yield, which after reduction with NaBH4 gave 4a,b in 75% and 84% yield, respectively. Condensation of 2a with diethylenetriamine leads to a complex mixture containing imidazolidine isomers, which was reduced in situ to afford 6a in 30% yield. Condensation of 2b with the same amine gave the stable diimidazolidine derivative 5b, which after crystallization was isolated as a pure compound in 80% yield and fully identified from analytical and 1H and 13C NMR data as a constitutional isomer with both imidazolidine rings located at the side of the pyrazole closer to the benzylic substituents. Reduction of 5b with NaBH4 afforded the polyamine 6b in 86% yield. Protonation constants of 4a,b and 6a,b have been determined by potentiometric methods in the pH 2-11 range, and their protonation sequences were established by a 1H and 13C NMR study in D2O at variable pH. For each compound, the number of protonation constants equals the number of nitrogens in the side chains. In the pH range studied, the pyrazole rings are not involved in protonation or deprotonation processes.
