A series of π-extended aromatic indenofluorene (IF) analogues with naphthalene and anthracene cores have been synthesized through acid-catalyzed intramolecular cyclization. The regioselectivity of the reaction is controlled by a combination of steric and electronic factors and in some cases several possible regioisomers have resulted from the same precursor. The effects of ring connectivity on the optoelectronic properties were investigated by DFT calculations, absorption/emission spectroscopy, cyclic voltammetry, and spectroelectrochemical studies. All regioisomers exhibited a redshift of their absorption/emission bands relative to the parent IF analogues, but the magnitude of this shift and other optoelectronic properties (luminescence quantum yield, etc.) depends on the ring connectivity in a less obvious manner.
Polyamidoamine (PAMAM) dendrimers were covalently immobilized on multi-walled carbon nanotubes (MWNT) by two "grafting to" strategies. We demonstrate the existence of non-covalent interactions between the two components but outline the superiority of our two grafting approaches, namely xanthate and click chemistry. MWNT surfaces were functionalized with activated ester and propargylic moieties prior to their reaction with PAMAM or azido-PAMAM dendrimers, respectively. The grafting of PAMAM generations 0 to 3 was evaluated with X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), and transmission electron microscopy (TEM). The versatility of our hybrids was demonstrated by post-functionalization sequences involving copper alkyne-azide cycloaddition (CuAAC). We synthesized homogeneous supported iridium complexes at the extremities of the dendrimers. In addition, our materials were used as templates for the encapsulation of Pd nanoparticles (NPs), validating our nanocomposites for catalytic applications. The palladium-based catalyst was active for carbonylative coupling over five consecutive runs without loss of activity.
Chemical functionalization of nanocarbons is essential for further applications in various fields. We developed a facile, inexpensive, and gram‐scale one‐pot route towards alkynyl‐functionalized nanocarbons. Nucleophilic addition/propargylic capture places alkyne moieties at the surface of carbon nanotubes (CNTs) and graphene. Thermogravimetric analysis coupled with mass spectrometry and Raman analysis confirmed the efficiency of this process. Conductivity measurements demonstrated the maintenance of the CNT electrical properties. The attached alkynyl moieties were reacted with various azide derivatives through the click‐Huisgen [3+2] cycloaddition and characterized with XPS. The efficient addition of those derivatives enables the application of our finding in various fields. This route is a reliable and convenient alternative to the known diazonium functionalization and oxidation‐esterification reactions to graft alkyne groups.
Iridium(III) and ruthenium(II) polypyridyl based photocatalysts have been prepared and their structure determined using 1H NMR, HR‐MS and single crystal XRD. Their spectroscopic and electrochemical properties have been studied by UV‐vis absorption, emission spectroscopy and cyclic voltammetry. These complexes have been used as photoredox homogeneous catalysts in an intramolecular cyclization model reaction in which they show high activity. They have been covalently anchored on graphene oxide (GO) via an esterification reaction and non‐covalently fixed on reduced graphene oxide (rGO) via pyrene moieties. Heterogenized complexes exhibit good photocatalytic activities and, interestingly, the use of a pyrene‐derivatized Ir(III) terpyridine‐based complex highlights an unexpected “on/off” effect of the photocatalytic activity triggered by the presence or absence of rGO.
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