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The synthesis of complex and hybrid oxide microstructures is of fundamental interest and practical applications. However, the design and synthesis of such structures is a challenging task. A solution‐phase process to synthesize complex silica and silica–titania hybrid microstructures was developed by exploiting the emulsion‐droplet‐based step‐by‐step growth featuring shape control. The strategy is robust and can be extended to the preparation of complex hybrid structures consisting of two or more materials, with each having its own shape.  相似文献   

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Tungsten tryst : A 4‐H‐butatrienylidene complex of tungsten was successfully isolated and structurally characterized. It undergoes a unique self‐coupling, which leads to a dimer (see picture; P pink, O red) with a cross‐conjugated π system and with electrochemically and magnetically active metal centers.

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Dibenzo‐24‐crown‐8 is studied herein as a flexible ligand able to adopt different conformations, as well as for the complexation of mercury. The recrystallization of dibenzo‐24‐crown‐8 (DB24C8) from dry THF gives a new polymorphic structure of this ligand. This new structure is described and compared to the literature compound. Additionally, coordination of this ligand to mercury iodide HgI2 is studied.  相似文献   

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Polyoxometalate (POM) complex (DODA)2[Mo6O19] with a symmetrical linear structure was prepared conveniently by replacing the tetrabutylammonium (TBA) counterions of Lindquist‐type cluster (TBA)2[Mo6O19] with cationic surfactant dioctadecyldimethylammonium (DODA). A helical self‐assembled structure of the complex was formed in dichloromethane/propanol. The dynamically reversible transformation between helical and spherical assemblies on alternate UV irradiation and H2O2 oxidation was characterized by SEM, TEM, and UV/Vis studies. The redox‐controlled morphology change is modulated by variation of the electrostatic interactions between the inorganic polyanion and the organic cation DODA through controlling the redox properties of the POM component, as shown by the XRD, X‐ray photoelectron spectroscopic, and 1H NMR measurements. The strategy applied herein is a unique example of targeted smart and helical assembly of POM complexes.  相似文献   

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The photoluminescence (PL) properties of a metal‐free organoboron complex, bis(4‐iodobenzoyl)methanatoboron difluoride ( 1BF2 ), were elucidated. At room temperature, 1BF2 emits blue fluorescence (FL) in nBuCl upon photoexcitation. In contrast, crystals of 1BF2 emit green PL comprised of FL and phosphorescence (PH). The room‐temperature PH of crystalline 1BF2 is a consequence of 1) suppression of thermal deactivation of the S1 and T1 excited states and 2) enhancement of intersystem crossing (ISC) from the S1 to T2 or T1. The results of X‐ray crystallographic and theoretical studies supported the proposal that the former (1) is a result of intermolecular interactions caused by π‐stacking in the rigid crystal packing structure of 1BF2 . The latter (2) is an effect of not only the heavy‐atom effect of iodine, but also the continuous π‐stacking alignment of 1BF2 molecules in crystals, which leads to a forbidden S1→S0 transition and a small energy gap between the S1 and T2 or T1.  相似文献   

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Gold–carbene complexes are essential intermediates in many gold‐catalyzed organic‐synthetic transformations. While gold–carbene complexes with direct, vinylogous, or phenylogous heteroatom substitution have been synthesized and characterized, the observation in the condensed phase of electronically non‐stabilized gold–carbenes has so far remained elusive. The sterically extremely shielded, emerald‐green complex [IPr**Au=CMes2]+[NTf2]? has now been synthesized, isolated, and fully characterized. Its absorption maximum at 642 nm, in contrast to 528 nm of the red‐purple carbocation [Mes2CH]+, clearly demonstrates that gold is more than just a “soft proton”.  相似文献   

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