based DSPEC using a zinc porphyrin (ZnP) sensitizer and a TEMPO organo-catalyst that quite efficiently catalyzes light driven oxidation of methoxybenzyl alcohol into aldehyde. Two dyads ZnP-TEMPO, differing by the anchoring group (carboxylic acid and hydroxamic acid) on ZnP, were prepared and their electrochemical, absorption, emission properties were recorded and quantum chemical modelling was realized. The photovoltaic performances in DSSCs were first examined in order to optimize the dyeing conditions and compare the relative efficiencies of the compounds. The dyads substituted with TEMPO outperform the reference zinc porphyrin lacking TEMPO with a much higher Jsc and Voc. The photocatalytic properties after immobilization on TiO 2 nanocrystalline films towards para-methoxy benzyl alcohol oxidation were explored in borate buffer and in acetonitrile electrolyte. In borate buffer, the optimal pH was 8 and using the dyad ZnP-TEMPO anchored with hydroxamic acid, para-methoxy benzaldehyde was selectively produced with average photocurrent density of 200 A/cm 2 , a faradaic efficiency of 82%, a TON of 26, and a TOF of 47 h -1 . In acetonitrile in presence of 0.1 M of N-methyl-imidazole, the same dyad gives an average photocurrent density of about 100 A/cm 2 , a faradaic efficiency of 76%, a TON of 13, and a TOF of 24 h -1 . The stability of the anchor is crucial in acetonitrile electrolyte, where the dyad is quite soluble, since only the dyad functionalized with hydroxamic acid is compatible with these organic solvent conditions. Overall this study paves the way to the development of more efficient and probably more stable TiO 2 based DSPECs for alcohol oxidation that could advantageously complement those devoted to water oxidation.

Carbon dots and nitrogen doped carbon dots were effectively synthesized and characterized. Their use as H2 light harvesters was examined in the presence of three different cobalt-based catalysts and tris(carboxyethyl)phosphine/ascorbic...

In this work, the self assembly ability of chromophores covalently linked to aliphatic dipeptides is described. Altering various parameters such as the protecting group, the solvent mixture, the dipeptide and the chromophore resulted in different nanostructures.Interestingly, a peptide-porphyrin hybrid is capable of forming a hydrogel in HFIP-water solvent mixture.Living natural systems utilize self-assembly in order to fulfil their functions; thus, understanding the basic aspects of this process takes us a step closer to the comprehension of life. 1 Numerous examples in nature have inspired supramolecular scientists to synthesize molecules with self-assembling ability aiming at the construction of materials with improved properties. 2 Self-assembled architectures that mimic chlorophylls and bacteriochlorophylls in nature are of great interest for light harvesting applications. 3 A variety of bioinspired building blocks have been explored for the fabrication of self-assembling molecules including peptides, 4,5 nucleic acids, 6,7 peptide nucleic acids, 8,9 lipids etc. Of the small peptides, diphenylalanine (FF), the basic structural motif for the Alzheimer's beta amyloid polypeptide, is an aromatic dipeptide that has been extensively investigated for its self-assembling properties. 10,11 More specifically, a great number of chromophores such as porphyrins, 12-15 boron-dipyrromethenes, 16 corroles, 17 polyoxometallates 18 and ferrocene 19 have been covalently connected to FF resulting in hybrids that retained the ability to form well-defined nanostructures. In addition, small aliphatic peptides have also been investigated for their self-assembly ability. 20 In a recent example, Yan and co-workers reported that a short peptide based on

In this study, a highly efficient photocatalytic H2 production system is developed by employing porphyrins as photocatalysts. Palladium and platinum tetracarboxyporphyrins (PdTCP and PtTCP) are adsorbed or coadsorbed onto TiO2 nanoparticles (NPs), which act as the electron transport medium and as a scaffold that promotes the self‐organization of the porphyrinoids. The self‐organization of PdTCP and PtTCP, forming H‐ and J‐aggregates, respectively, is the key element for H2 evolution, as in the absence of TiO2 NPs no catalytic activity is detected. Notably, J‐aggregated PtTCPs are more efficient for H2 production than H‐aggregated PdTCPs. In this approach, a single porphyrin, which self‐organizes onto TiO2 NPs, acts as the light harvester and simultaneously as the catalyst, whereas TiO2 serves as the electron transport medium. Importantly, the concurrent adsorption of PdTCP and PtTCP onto TiO2 NPs results in the most efficient catalytic system, giving a turnover number of 22,733 and 30.2 mmol(H2) g(cat)−1.

In this work, the diphenylalanine dipeptide was covalently attached to a tripyridyl porphyrin macrocycle and conveyed self-assembling properties to the resulting hybrid. This hybrid was metallated with non-noble metals, Zn and Sn, and investigated toward photocatalytic hydrogen evolution. The Sn derivative, SnPy3P-FF, was able to produce hydrogen photocatalytically in the presence of a known cobaloxime catalyst and TEOA as a sacrificial electron donor. When the self-assembling nanostructures of SnPy3P-FF were employed in the photocatalytic system, enhanced hydrogen production was observed. Fluorescence and transient absorption experiments were performed in order to shed light on the electron transfer processes that take place during the photocatalysis.

Herein, we illustrate the preparation of a covalent connected peptide-porphyrin hybrid (Fmoc-FF-(Zn)Por). Thorough investigation of its self-organization features demonstrated that Fmoc-FF-(Zn)Por can self-assembly into spheres and fibrils by using different...

In this study, we report the utilization of BODIPY-(Zn)­Porphyrin hybrids in photocatalytic H2 production from water. These entities were applied as photosensitizers upon their chemisorption onto the surface of platinum-doped titanium dioxide nanoparticles (Pt-TiO2), which acted as photocatalysts. To evaluate the impact of the different connectivity between the chromophores in photocatalytic in H2 evolution, we employed two diverse BODIPY-(Zn)­Porphyrin entities, in which the BODIPY moiety is either covalently attached (BDP-Por) or axially coordinated (BDP­(Im)-Por) with the (Zn)­Porphyrin. The covalently connected dyad (BDP-Por) presented higher catalytic activity (17 500 TONs) compared to the axial coordinated (BDP­(Im)-Por, 13 700 TONs). In BDP-Por dyad, an additional BDP­(Im) moiety was introduced and the formed hybrid (BDP-Por-BDP­(Im)) outperformed the aforementioned systems, due to the enhanced light harvesting ability. Overall, we developed highly efficient dye-sensitized photocatalytic systems (DSPs) based on noble-metal-free photosensitizers reaching 18 600 turnover numbers (TONs) and 225 mmol­(H2) g­(cat)−1 h–1.

We report a comparison between a series of zinc and tin porphyrins as photosensitizers for photochemical hydrogen evolution using cobaloxime complexes as molecular catalysts. Among all the chromophores tested, only the positively charged zinc porphyrin, [ZnTMePyP4+]­Cl4, and the neutral tin porphyrin derivatives, Sn­(OH)2TPyP, Sn­(Cl2)­TPP-[COOMe]4, and Sn­(Cl2)­TPP-[PO­(OEt)2]4, were photocatalytically active. Hydrogen evolution was strongly affected by the pH value as well as the different concentrations of both the sensitizer and the catalyst. A comprehensive photophysical and electrochemical investigation was conducted in order to examine the mechanism of photocatalysis. The results derived from this study establish fundamental criteria with respect to the design and synthesis of porphyrin derivatives for their application as photosensitizers in photoinduced hydrogen evolution.