Cyclometalated IrIII Complexes with Substituted 1,10‐Phenanthrolines: A New Class of Efficient Cationic Organometallic Second‐Order NLO Chromophores

Cyclometalated cationic Ir^III complexes with substituted 1,10‐phenanthrolines (1,10‐phen), such as [Ir(ppy)₂(5‐R‐1,10‐phen)]Y (ppy=cyclometalated 2‐phenylpyridine; R=NO₂, H, Me, NMe₂; Y^?=PF₆^?, C₁₂H₂₅SO₃^?, I^?) and [Ir(ppy)₂(4‐R,7‐R‐1,10‐phen)]Y (R=Me, Ph) are characterized by a significant second‐order optical non linearity (measured by the electrical field induced second harmonic generation (EFISH) technique). This nonlinearity is controlled by MLCT processes from the cyclometalated Ir^III, acting as a donor push system, to π* orbitals of the phenanthroline, acting as an acceptor pull system. Substitution of cyclometalated 2‐phenylpyridine by the more π delocalized 2‐phenylquinoline (pq) or benzo[h]quinoline (bzq) or by the sulfur‐containing 4,5‐diphenyl‐2‐methyl‐thiazole (dpmf) does not significantly affect the μβ absolute value, which instead is affected by the nature of the R substituents on the phenanthroline, the higher value being associated with the electron‐withdrawing NO₂ group. By using a combined experimental (the EFISH technique and ¹H and ¹⁹F PGSE NMR spectroscopy) and theoretical (DFT, time‐dependent‐DFT (TDDFT), sum over states (SOS) approach) investigation, evidence is obtained that ion pairing, which is controlled by the nature of the counterion and by the concentration, may significantly affect the μβ values of these cationic NLO chromophores. In CH₂Cl₂, concentration‐dependent high absolute values of μβ are obtained for [Ir(ppy)₂(5‐NO₂‐1,10‐phen)]Y if Y is a weakly interacting anion, such as PF₆^?, whereas with a counterion, such as C₁₂H₂₅SO₃^? or I^?, which form tight ion‐pairs, the absolute value of μβ is lower and quite independent of the concentration. This μβ trend is partially due to the perturbation of the counterion on the LUMO π* levels of the phenanthroline. The correlation between the μβ value and dilution shows that the effect of concentration is a factor that must be taken into careful consideration.     

化学发光酶免疫分析研究进展

叙述了化学发光免疫分析的分类及特点,从发光底物、增强剂、过氧化物酶、过氧化物及其他方面,对鲁米诺类化合物化学发光酶免疫分析的进展进行了综述,引用文献34篇。     

Moduli of Polarized Calabi–Yau Pairs

We prove that the irreducible components of the moduli space of polarized Calabi–Yau pairs are projective.     

Ion‐Pair SN2 Substitution: Activation Strain Analyses of Counter‐Ion and Solvent Effects

The ion‐pair S_N2 reactions of model systems M_nF^n?1+CH₃Cl (M⁺=Li⁺, Na⁺, K⁺, and MgCl⁺; n=0, 1) have been quantum chemically explored by using DFT at the OLYP/6‐31++G(d,p) level. The purpose of this study is threefold: 1) to elucidate how the counterion M⁺ modifies ion‐pair S_N2 reactivity relative to the parent reaction F^?+CH₃Cl; 2) to determine how this influences stereochemical competition between the backside and frontside attacks; and 3) to examine the effect of solvation on these ion‐pair S_N2 pathways. Trends in reactivity are analyzed and explained by using the activation strain model (ASM) of chemical reactivity. The ASM has been extended to treat reactivity in solution. These findings contribute to a more rational design of tailor‐made substitution reactions.     

Ion‐Pairing Assemblies Based on Pentacyano‐Substituted Cyclopentadienide as a π‐Electronic Anion

Pentacyanocyclopentadienide (PCCp^?), a stable π‐electronic anion, provided various ion‐pairing assemblies in combination with various cations. PCCp^?‐based assemblies exist as single crystals and mesophases owing to interionic interactions with π‐electronic and aliphatic cations with a variety of geometries, substituents, and electronic structures. Single‐crystal X‐ray analysis revealed that PCCp^? formed cation‐dependent arrangements with contributions from charge‐by‐charge and charge‐segregated assembly modes for ion pairs with π‐electronic and aliphatic cations, respectively. Furthermore, some aliphatic cations gave dimension‐controlled organized structures with PCCp^?, as observed in the mesophases, for which synchrotron XRD analysis suggested the formation of charge‐segregated modes. Noncontact evaluation of conductivity for (C₁₂H₂₅)₃MeN⁺ ? PCCp^? films revealed potential hole‐transporting properties, yielding a local‐scale hole mobility of 0.4 cm² V^?1 s^?1 at semiconductor–insulator interfaces.