Kinetics and mechanisms of the complexation of aqueous lanthanide ions by 4-(2-pyridylazo)resorcinol †

Molecular-Level Insights into N–N π-Bond Rotation in the pH-Induced Interfacial Isomerization of 5-Octadecyloxy-2-(2-pyridylazo)phenol Monolayer Investigated by Sum Frequency Generation Vibrational Spectroscopy

“…It is needed to mention that the equilibrium constant ( k 1 ) in eq actually involves in several steps: water interaction, intramolecular hydrogen bonding formation and breaking, and intramolecular rearrangement. Such steps could be the rate-determining step . Earlier study indicated that the step where PAR molecules interact with the surrounding water molecules in the vicinity of the reaction site has a rate constant in the order of 10 –5 –10 –6 s –1 and increases with the hydrogen-bond strength, which matches well with our result of k 1 [OH – ].…”

“…Such steps could be the rate-determining step. 63 Earlier study indicated that the step where PAR molecules interact with the surrounding water molecules in the vicinity of the reaction site has a rate constant in the order of 10 −5 −10 −6 s −1 and increases with the hydrogenbond strength, 64 which matches well with our result of k 1 [OH − ].…”

Sodium 4-(2-pyridinyldiazenyl)resorcinolate monohydrate and ammonium 2,4-dinitro-1-naphthalenolate from powder diffraction data

“…However, according to INDO/S calculations, the effect of the pyridine twisting on the position of the absorption maximum is not large, ca 900 cm À1 , thus it can be overshadowed by other effects, such as intermolecular hydrogen bonding. The twist of the pyridine ring in the solvated monoanion is in line with the ®nding that in the ®rst stage of complex formation, PAR coordinates to the metal ion via the pyridine N atom, and in the second stage (slow), a bond to the azo-N atom forms (Shi et al, 1998).…”

Self-Assembly Mechanism of a Bimetallic Europium Triple-Stranded Helicate

“…This result strongly suggests that complexation of Eu by L could involve concerted structural changes which result in slower kinetics. [82][83][84][85][86][87] In solution and in the solid state, in the absence of coordinating cations, it has been shown that the monotopic tridentate receptors L 1 -L 7 (Table S2) adopt a trans-trans conformation in order to minimize dipole moment and reduce the steric hindrance when bulky substituents are introduced. 88 As well as the monotopic ligands, the ditopic strands exhibit transoid conformation in solution as demonstrated by 1 H-NMR spectroscopy (NOE effect).…”

“…The rate-limiting step obviously does not correspond to the simple desolvation of europium(III). This result strongly suggests that complexation of Eu by L could involve concerted structural changes which result in slower kinetics. − In solution and in the solid state, in the absence of coordinating cations, it has been shown that the monotopic tridentate receptors L 1 − L 7 (Table S2) adopt a trans−trans conformation in order to minimize dipole moment and reduce the steric hindrance when bulky substituents are introduced . As well as the monotopic ligands, the ditopic strands exhibit transoid conformation in solution as demonstrated by 1 H-NMR spectroscopy (NOE effect). ,,, During the coordination process, a rotation about the biaryl bond, already observed for copper(I) complexation with poly(2,2‘-bipyridine) ligands , and transition metal complexes formed with tridentate terpyridine ligands, should occur to allow multiple ion coordination.…”