132268-08-7Relevant academic research and scientific papers
Binuclear complexes of Ni(i) from 4-terphenyldithiophenol
Koch, Felix,Schubert, Hartmut,Sirsch, Peter,Berkefeld, Andreas
, p. 13315 - 13324 (2015)
Binuclear complexes of Ni(i) have been prepared from a 4-terphenyldithiophenol ligand. Steric effects were found to determine the formation of coordination isomeric structures that differ in the nature of metal-to-ligand bonding. Coordination of spatially
Novel preorganized hemispherands to encapsulate rare earth ions: Shielding and ligand deuteration for prolonged lifetimes of excited Eu3+ ions
Oude Wolbers, Manon P.,Van Veggel, Frank C. J. M.,Snellink-Ru?l, Bianca H. M.,Hofstraat, Johannes W.,Geurts, Frank A. J.,Reinhoudt, David N.
, p. 138 - 144 (2007/10/03)
Quenching of the luminescent excited state of Eu3+ ions by C-H high-vibrational modes was studied by deuteration of the encapsulating ligand and the solvent. Novel polydentate hemispherands providing nine donor atoms, which form overall neutral complexes with rare earth ions, were synthesized in nine steps, allowing the easy incorporation of deuterium atoms (IIa-d·Eu3+). The introduction of tert-butyl groups at the aromatic rings of the ligand further increased the solubility of the complexes in organic solvents (29·Eu3+ and 34·Eu3+). Photophysical studies, viz., luminescence spectra and lifetime measurements, revealed that significant quenching of the Eu3+ excited state is induced by nearby C-H vibrational modes. Substitution of these quenching C-H modes for C-D bonds in the azacrown bridge leads to an enhancement of the luminescent lifetime by a factor of 1.5. C-H high-vibrational modes of the pendant arms which are at a larger distance to the Eu3+ ion than the azacrown bridge hydrogen atoms (determined from the MD calculations) are less efficient quenchers. The number of coordinating methanol molecules to 11a·Eu3+, 29·Eu3+, and 34·Eu3+ estimated by the 'Horrocks equation' is 0.9, 1.2, and 1.9, respectively, as was predicted by MD calculations. Moreover, the experimental data show that quenching of the excited state of well-shielded Eu3+ ions by the C-H modes of the ligand is of the e order of magnitude as quenching by one O-H mode.
Binucleating ligands: Synthesis of acyclic achiral and chiral Schiff base-pyridine and Schiff base-phosphine ligands
Lam, Fung,Xu, Jia Xi,Chan, Kin Shing
, p. 8414 - 8418 (2007/10/03)
5-tert-Butyl-3-(2′-pyridyl)salicyaldehyde and 5-tert-butyl-3-(diphenylphosphino)salicyaldehyde were synthesized from 4-tert-butylphenol in good overall yields. Condensation of the salicyaldehydes with 2,3-diamino-2,3-dimethylbutane afforded the desired dinucleating Schiff base-pyridine and Schiff base-phosphine ligands, respectively. 5-tert-Butyl-3-(2′-pyridyl)salicyaldehyde reacted with optically active 1,2-diaminocyclohexanes to give chiral dinucleating Schiff base-pyridine ligands.
Synthesis of acyclic dinucleating Schiff base-pyridine and Schiff base-phosphine ligands
Lam, Fung,Chan, Kin Shing
, p. 919 - 922 (2007/10/02)
5-tert-butyl-3-pyridyl-salicyaldehyde and 5-tert-butyl-3-diphenylphosphino-salicyaldehyde have been synthesized from 4-tert-butylphenol in good overall yields. Condensation of the salicyaldehydes with 2,3-diamino-2,3-dimethylbutane afforded the desired dinucleating Schiff base-pyridine and Schiff base-phosphine ligands respectively.
Improved Acylation Rates within Cyclodextrin Complexes from Flexible Capping of the Cyclodextrin and from Adjustment of the Substrate Geometry
Breslow, Ronald,Czarniecki, Michael F.,Emert, Jack,Hamaguchi, Hiroshi
, p. 762 - 770 (2007/10/02)
The acylation of β-cyclodextrin by bound substrates has been studied as a model for serine acylase enzymes such as chymotrypsin.Molecular model building suggested that previously examined substrates, which had given acylation rates only a few hundred times accelerated over the hydrolysis rates, were not optimal geometrically.In our work the geometry for such processes has been improved by fashioning an "intrusive floor" on the cyclodextrin cavity, leading to improved rates.Greater improvements have come from substrate modification, using substrates based on the cinnamic acid, adamantane, and ferrocene frameworks.The rates correlate well with the geometric predictions from molecular models.The best case leads to an acceleration of acylation, relative to hydrolysis, of 106-107-fold, exceeding that for chymotrypsin with p-nitrophenyl acetate.
