Photocatalytic recovery of metals by Lindqvist-type polyoxometalate–porphyrin copolymer

Hybrid polyoxometalate–porphyrin copolymeric films can be obtained by the electro-oxidation of 5,15-ditolyl porphyrin (H$_{\mathbf{2}}$T$_{\mathbf{2}}$P) and zinc-$\beta$-octaethylporphyrin (ZnOEP) in the presence of the Lindqvist-type polyoxovanadates \mathrm{TBA}_{2}[\mathrm{V}_{6}\mathrm{O}_{13} \lbrace (\mathrm{OCH}_{2})_{3}\mathrm{CNHCO} (4\mbox {-}\mathrm{C}_{5}\mathrm{H}_{4}\mathrm{N})\rbrace _{2}] (Py-V$_{\mathbf{6}}$O$_{\mathbf{13}}$-Py). The photocatalytic properties of these films have been studied for the reduction of silver and platinum ions. In these hybrid materials, porphyrins can be excited by visible light and then play the role of photosensitizers able to give electrons to the polyoxovanadates catalysts

Photocatalytic recovery of metals by Lindqvist-type polyoxometalate–porphyrin copolymer

Hybrid polyoxometalate–porphyrin copolymeric films can be obtained by the electro-oxidation of 5,15-ditolyl porphyrin (H$_{\mathbf{2}}$T$_{\mathbf{2}}$P) and zinc-$\beta$-octaethylporphyrin (ZnOEP) in the presence of the Lindqvist-type polyoxovanadates \mathrm{TBA}_{2}[\mathrm{V}_{6}\mathrm{O}_{13} \lbrace (\mathrm{OCH}_{2})_{3}\mathrm{CNHCO} (4\mbox {-}\mathrm{C}_{5}\mathrm{H}_{4}\mathrm{N})\rbrace _{2}] (Py-V$_{\mathbf{6}}$O$_{\mathbf{13}}$-Py). The photocatalytic properties of these films have been studied for the reduction of silver and platinum ions. In these hybrid materials, porphyrins can be excited by visible light and then play the role of photosensitizers able to give electrons to the polyoxovanadates catalysts

Paramagnetic Molecular Grippers: The Elements of Six-State Redox Switches

The development of semiquinone-based resorcin[4]arene cavitands expands the toolbox of switchable molecular grippers by introducing the first paramagnetic representatives. The semiquinone (SQ) states were generated electrochemically, chemically, and photochemically. We analyzed their electronic, conformational, and binding properties by cyclic voltammetry, ultraviolet/visible (UV/vis) spectroelectrochemistry, electron paramagnetic resonance (EPR) and transient absorption spectroscopy, in conjunction with density functional theory (DFT) calculations. The utility of UV/vis spectroelectrochemistry and EPR spectroscopy in evaluating the conformational features of resorcin[4]arene cavitands is demonstrated. Guest binding properties were found to be enhanced in the SQ state as compared to the quinone (Q) or the hydroquinone (HQ) states of the cavitands. Thus, these paramagnetic SQ intermediates open the way to six-state redox switches provided by two conformations (open and closed) in three redox states (Q, SQ, and HQ) possessing distinct binding ability. The switchable magnetic properties of these molecular grippers and their responsiveness to electrical stimuli has the potential for development of efficient molecular devices

Spectro-electrochemical toolbox for monitoring and controlling quinone-mediated redox-driven molecular gripping

ISSN:0013-4686ISSN:1873-3859ISSN:00003198

Metal-acetylide addition to tetracyanoethylene

ISSN:0040-403

Push-pull chromophores by reaction of 2,3,5,6-tetrahalo-1,4-benzoquinones with 4-(N,N-dialkylanilino)acetylenes

A series of new push-pull chromophores were synthesized from electron-rich 4-(N,N-dialkylanilino) acetylenes and 2,3,5,6-tetrahalo-1,4-benzoquinones. The reactivity of the latter differs substantially from that of the previously investigated 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ). The transformation with fluoranil gave orange-colored, bis-donor-substituted chromophores with a tricyclic, cyclobutene-fused dihydrobenzofuranone core. In contrast, the reaction with chioranil yielded mono donor-substituted, blue 1,4-benzoquinone-based chromophores, which were further reacted with tertiary amines to form bis-donor-substituted push-pull systems. The structures of the new chromophores were confirmed by X-ray analysis, and mechanisms for their formation are proposed. They feature intense intramolecular charge-transfer bands in the visible region, and their optoelectronic properties were investigated by UV/Vis spectroscopy, electrochemistry, and computational analysis

Acetylenic scaffolding with derivatives of tetrathiafulvalene

A selection of tetrathiafulvalene (TTF) derivatives containing acetylenic moieties have been synthesized and studied by cyclic voltammetry and UV-Vis absorption spectroscopy. Ionization energy calculations on some extended TTFs were carried out employing the DFT method. Key words. Alkynes – $\pi$-donors – tetrathiafulvalene.

Synthesis of Cyano-Substituted Diaryltetracenes from Tetraaryl[3] cumulenes**

A versatile, two-step synthesis of highly substituted, cyano-functionalized diaryltetracenes has been developed, starting from easily accessible tetraaryl[3]cumulenes. This unprecedented transformation is initiated by [2+2] cycloaddition of tetracyanoethylene (TCNE) to the proacetylenic central double bond of the cumulenes to give an intermediate zwitterion, which after an electrocyclization cascade and dehydrogenation yields 5,5,11,11-tetracyano-5,11-dihydrotetracenes in a one-pot procedure. A subsequent copper-assisted decyanation/aromatization provided the target 5,11-dicyano-6,12-diaryltetracene derivatives. All of the postulated structures were confirmed by X-ray crystallography. The new chromophores are thermally highly stable and feature promising fluorescence properties for potential use in optoelectronic devices. They are selective chemosensors for Cu-I ions, which coordinate to one of the CN substituents and form a 1:1 complex with an association constant of K-a=1.5x10(5)Lmol(-1) at 298K