Correction: Perylene-derivative singlet exciton fission in water solution.

[This corrects the article DOI: 10.1039/D4SC04732J.].

Perylene-derivative singlet exciton fission in water solution.

We provide direct evidence of singlet fission occurring with water-soluble compounds. We show that perylene-3,4,9,10-tetracarboxylate forms dynamic dimers in aqueous solution, with lifetimes long enough to allow intermolecular processes such as singlet fission. As these are transient dimers rather than stable aggregates, they retain a significant degree of disorder.

Time-Resolved Mechanistic Depiction of Photoinduced CO Reduction Catalysis on a Urea-Modified Iron Porphyrin.

The development of functional artificial photosynthetic devices relies on the understanding of mechanistic aspects involved in specialized photocatalysts. Modified iron porphyrins have long been explored as efficient catalysts for the light-induced reduction of carbon dioxide (CO) towards solar fuels. In spite of the advancements in homogeneous catalysis, the development of the next generation of catalysts requires a complete understanding of the fundamental photoinduced processes taking place prior to and after activation of the substrate by the catalyst.

Proton Domino Reactions at an Imidazole Relay Control the Oxidation of a Tyr-His Artificial Mimic of Photosystem II.

A close mimic of P680 and the Tyrosine-Histidine pair in photosystem II (PS II) has been synthesized using a ruthenium chromophore and imidazole-phenol ligands. The intramolecular oxidation of the ligands by the photoproduced Ru(III) species is characterized by a small driving force, very similar to PS II where the complexity of kinetics was attributed to the reversibility of electron transfer steps. Laser flash photolysis revealed biphasic kinetics for ligand oxidation.

Phase II randomized trial comparing metronomic anthracycline-containing chemotherapy versus standard schedule in untreated HER2 negative advanced breast cancer: activity and quality of life results of the GOIM 21003 trial.

Background: Optimizing chemotherapy to achieve disease and symptoms control is a noteworthy purpose in advanced breast cancer (ABC). We reported the activity and quality of life of a phase II study, comparing metronomic regimen with standard schedule as first line chemotherapy for ABC.

Methods: Patients with HER2 negative ABC were randomized to non-pegylated liposomal doxorubicin (NPLD, 60 mg/m2 every 3 weeks) and cyclophosphamide (CTX, 600 mg/m2 every 3 weeks) (Arm A) or NPLD (20 mg/m2 day, on day 1, 8 and 15 every 4 weeks) and metronomic daily oral CTX 50 mg (ARM B).

Second Coordination Sphere Effect Shifts CO to CO Reduction by Iron Porphyrin from Fe to Fe.

Iron porphyrins are among the most studied molecular catalysts for carbon dioxide (CO ) reduction and their reactivity is constantly being enhanced through the implementation of chemical functionalities in the second coordination sphere inspired by the active sites of enzymes. In this study, we were intrigued to observe that a multipoint hydrogen bonding scheme provided by embarked urea groups could also shift the redox activation step of CO from the well-admitted Fe(0) to the Fe(I) state. Using EPR, resonance Raman, IR and UV-Visible spectroscopies, we underpinned a two-electron activation step of CO starting from the Fe(I) oxidation state to form, after protonation, an Fe(III)-COOH species.

Proton-controlled Action of an Imidazole as Electron Relay in a Photoredox Triad.

Electron relays play a crucial role for efficient light-induced activation by a photo-redox moiety of catalysts for multi-electronic transformations. Their insertion between the two units reduces detrimental energy transfer quenching while establishing at the same time unidirectional electron flow. This rectifying function allows charge accumulation necessary for catalysis.

Tracking light-induced electron transfer toward O in a hybrid photoredox-laccase system.

Photobiocatalysis uses light to perform specific chemical transformations in a selective and efficient way. The intention is to couple a photoredox cycle with an enzyme performing multielectronic catalytic activities. Laccase, a robust multicopper oxidase, can be envisioned to use dioxygen as a clean electron sink when coupled to an oxidation photocatalyst.

Phthalocyanine as a Bioinspired Model for Chlorophyll f-Containing Photosystem II Drives Photosynthesis into the Far-Red Region.

The textbook explanation that P pigments are the red limit to drive oxygenic photosynthesis must be reconsidered by the recent discovery that chlorophyll f (Chlf)-containing Photosystem II (PSII) absorbing at 727 nm can drive water oxidation. Two different families of unsymmetrically substituted Zn phthalocyanines (Pc) absorbing in the 700-800 nm spectral window and containing a fused imidazole-phenyl substituent or a fused imidazole-hydroxyphenyl group have been synthetized and characterized as a bioinspired model of the Chlf/Tyrosine /Histidine cofactors of PSII. Transient absorption studies in the presence of an electron acceptor and irradiating in the far-red region evidenced an intramolecular electron transfer process.

Singlet fission in naturally-organized carotenoid molecules.

We have investigated the photophysics of aggregated lutein/violaxanthin in daffodil chromoplasts. We reveal the presence of three carotenoid aggregate species, the main one composed of a mixture of lutein/violaxanthin absorbing at 481 nm, and two secondary populations of aggregated carotenoids absorbing circa 500 and 402 nm. The major population exhibits an efficient singlet fission process, generating μs-lived triplet states on an ultrafast timescale.

Metronomic oral chemotherapy with cyclophosphamide plus capecitabine combined with trastuzumab (HEX) as first line therapy of HER-2 positive advanced breast cancer: A phase II trial of the Gruppo Oncologico Italia Meridionale (GOIM).

Background: The combination of chemotherapy plus anti HER-2 agents is the mainstay of HER-2 positive advanced breast cancer (ABC) therapy. We conducted a phase II trial testing activity and safety of trastuzumab and metronomic capecitabine/cyclophosphamide (HEX) as first-line therapy in HER-2 positive ABC.
Methods.

Spectroscopic Characterisation of a Bio-Inspired Ni-Based Proton Reduction Catalyst Bearing a Pentadentate N S Ligand with Improved Photocatalytic Activity.

Inspired by the sulfur-rich environment found in active hydrogenase enzymes, a Ni-based proton reduction catalyst with pentadentate N S ligand was synthesised. When coupled with [Ru(bpy) ] (bpy=2,2'-bipyridine) as photosensitiser and ascorbate as electron donor in a 1:1 mixture of dimethylacetamide and aqueous ascorbic acid/ascorbate buffer, the catalyst showed improved photocatalytic activity compared with a homologous counterpart bearing a tetradentate N S ligand. The mechanistic pathway of photoinduced hydrogen evolution was comprehensively analysed through optical transient absorption and time-resolved X-ray absorption spectroscopy, which revealed important electronic and structural changes in the catalytic system during photoirradiation.

Final results of a prospective study of scalp cooling in preventing chemotherapy-induced alopecia.

Alopecia is a distressing effect of cancer treatments. Our study examined efficacy and safety of scalp cooling to prevent chemotherapy-induced alopecia. Early breast cancer patients candidate to anthracycline and/or taxane were eligible.

Second-Sphere Biomimetic Multipoint Hydrogen-Bonding Patterns to Boost CO Reduction of Iron Porphyrins.

Inspired by nature's orchestra of chemical subtleties to activate and reduce CO , we have developed a family of iron porphyrin derivatives in to which we have introduced urea groups functioning as multipoint hydrogen-bonding pillars on the periphery of the porphyrinic ring. This structure closely resembles the hydrogen-bond stabilization scheme of the carbon dioxide (CO ) adduct in the carbon monoxide dehydrogenase (CODH). We found that such changes to the second coordination sphere significantly lowered the overpotential for CO reduction in this family of molecular catalysts and importantly increased the CO binding rate while maintaining high turnover frequency (TOF) and selectivity.

Water Molecules Gating a Photoinduced One-Electron Two-Protons Transfer in a Tyrosine/Histidine (Tyr/His) Model of Photosystem II.

We investigate a biomimetic model of a Tyr /His pair, a hydrogen-bonded phenol/imidazole covalently attached to a porphyrin sensitizer. Laser flash photolysis in the presence of an external electron acceptor reveals the need for water molecules to unlock the light-induced oxidation of the phenol through an intramolecular pathway. Kinetics monitoring encompasses two fast phases with distinct spectral properties.

Snapshots of Light Induced Accumulation of Two Charges on Methylviologen using a Sequential Nanosecond Pump-Pump Photoexcitation.

Methylviologen (MV) is perhaps the most used component as a reversible electron acceptor in photophysical studies. While MV is most commonly implicated as a reversible one-electron mediator, its electrochemical properties clearly evidence two successive one-electron reduction processes. In this report, we have investigated on the light driven two-charge accumulation on MV using a multicomponent system composed of the prototypical molecular photosensitizer [Ru(bpy)] and MV in the presence of ascorbate as reversible electron donor.

Intramolecular Photogeneration of a Tyrosine Radical in a Designed Protein.

Long-distance biological electron transfer occurs through a hopping mechanism and often involves tyrosine as a high potential intermediate, for example in the early charge separation steps during photosynthesis. Protein design allows for the development of minimal systems to study the underlying principles of complex systems. Herein, we report the development of the first ruthenium-linked designed protein for the photogeneration of a tyrosine radical by intramolecular electron transfer.

Secondary-Rim γ-Cyclodextrin Functionalization to Conjugate with C : Improved Efficacy as a Photosensitizer.

DIBAL-H-mediated demethylation provides a novel method to access secondary-rim functionalized γ-cyclodextrin. 2 ,3 -Dihydroxyl-per-O-methylated-γ-cyclodextrin has been obtained, whose conjugation with C allows access to the most water-soluble C conjugate described so far. The water solubility of 0.

Discordance in pathology report after central pathology review: Implications for breast cancer adjuvant treatment.

Aim: Pathological predictive factors are the most important markers when selecting early breast cancer adjuvant therapy. In randomized clinical trials the variability in pathology report after central pathology review is noteworthy. We evaluated the discordance rate (DR) and inter-rater agreement between local and central histopathological report and the clinical implication on treatment decision.

Photoreduction of the ferredoxin/ferredoxin-NADP(+)-reductase complex by a linked ruthenium polypyridyl chromophore.

Photosynthetic ferredoxin and its main partner ferredoxin-NADP(+)-reductase (FNR) are key proteins during the photoproduction of reductive power involved in photosynthetic growth. In this work, we used covalent attachment of ruthenium derivatives to different cysteine mutants of ferredoxin to trigger by laser-flash excitation both ferredoxin reduction and subsequent electron transfer from reduced ferredoxin to FNR. Rates and yields of reduction of the ferredoxin [2Fe-2S] cluster by reductively quenched Ru* could be measured for the first time for such a low redox potential protein whereas ferredoxin-FNR electron transfer was characterized in detail for one particular Ru-ferredoxin covalent adduct.

Oxidation catalysis via visible-light water activation of a [Ru(bpy)3](2+) chromophore BSA-metallocorrole couple.

Light induced enantioselective oxidation of an organic molecule with water as the oxygen atom source is demonstrated in a system where chirality is induced by a protein, oxygen atom transfer by a manganese corrole, and photocatalysis by ruthenium complexes.

Electron transfer activity of a de novo designed copper center in a three-helix bundle fold.

In this work, we characterized the intermolecular electron transfer (ET) properties of a de novo designed metallopeptide using laser-flash photolysis. α3D-CH3 is three helix bundle peptide that was designed to contain a copper ET site that is found in the β-barrel fold of native cupredoxins. The ET activity of Cuα3D-CH3 was determined using five different photosensitizers.

Synergistic "ping-pong" energy transfer for efficient light activation in a chromophore-catalyst dyad.

The synthesis of a porphyrin-Ru(II) polypyridine complex where the porphyrin acts as a photoactive unit and the Ru(II) polypyridine as a catalytic precursor is described. Comparatively, the free base porphyrin was found to outperform the ruthenium based chromophore in the yield of light induced electron transfer. Mechanistic insights indicate the occurrence of a ping-pong energy transfer from the (1)LC excited state of the porphyrin chromophore to the (3)MCLT state of the catalyst and back to the (3)LC excited state of the porphyrin unit.