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(D–π–A)˙− & (D–π–A)˙+ are generated in response to electrical stimulation. Unlike (D–π–A)˙−, (D–π–A)˙+ shows a systematically controllable substituent effect by the DPA R group ranging from electron-withdrawing F to electron-donating OMe group.

Finding a selective and efficient fragmentation process under ambient conditions is pivotal for the generation of fuels and chemical feedstocks from lignoceullosic biomass. In the present study, visible-light and amine-functionalized fullerene-based photocatalyst-promoted photodegradation reactions of dimeric β-O-4 and β-1 lignin model compounds, containing varying numbers of methoxy substituents on the arene ring, were explored to find and develop mild, eco-friendly photochemical techniques for efficient delignification. The results showed that, in contrast to well-known organic photoredox catalysts, amine-functionalized fullerene photocatalyst promoted photochemical reactions of lignin model compounds could lead to more efficient lignin fragmentation reactions through a pathway involving a selective C

Comparing to Ir(ppz)3, Ir(ppz)2(LX) emits a red-shifted phosphorescence of caused by an interligand energy transfer between the ppz and LX ligands. Especially, Ir(ppz)2(picOH) showed an intramolecular proton transfer in the excited singlet state.

Proton-coupled electron transfer (PCET), an essential process in nature with a well-known example of photosynthesis, has recently been employed in metal complexes to improve the energy conversion efficiency; however, a profound understanding of the mechanism of PCET in metal complexes is still lacking. In this study, we synthesized cyclometalated Ir complexes strategically designed to exploit the excited-state intramolecular proton transfer (ESIPT) of the ancillary ligand and studied their photoinduced PCET in both aprotic and protic solvent environments using femtosecond transient absorption spectroscopy and density functional theory (DFT) and time-dependent DFT calculations. The data reveal solvent-modulated PCET, where charge transfer follows proton transfer in an aprotic solvent and the temporal order of charge transfer and proton transfer is reversed in a protic solvent. In the former case, ESIPT from the enol form to the keto form, which precedes the charge transfer from Ir to the ESIPT ligand, improves the efficiency of metal-to-ligand charge transfer. This finding demonstrates the potential to control the PCET reaction in the desired direction and the efficiency of charge transfer by simply perturbing the external hydrogen-bonding network with the solvent.

Photooxygenation reactions of electron-deficient enaminoesters bearing an oxophilic silyl tether at the α-position of the nitrogen atom using methylene blue (MB) were explored to develop a mild and efficient photochemical strategy for oxidative C-C double bond cleavage reactions via singlet oxygen (

A typical metal complex has a central metal surrounded by multiple ligands, which greatly affect the properties of the whole complex. Although heteroleptic complexes often exhibit substantially different behaviors from homoleptic complexes, systematic studies to explain their origins have been rare. Of special importance is to understand why the heteroleptic metal complex shows a more complicated excited state relaxation dynamics than the homoleptic metal complex. To address this issue, we investigated the excited state relaxation dynamics of a heteroleptic Ir(III) complex, fac-Ir(ppy)2(ppz), and two homoleptic Ir(III) complexes, fac-Ir(ppy)3 and fac-Ir(ppz)3, using femtosecond X-ray transient absorption (fs-XTA) spectroscopy, ultrafast optical transient absorption (TA) spectroscopy, and DFT/TDDFT calculation. The data show that the ultrafast relaxation dynamics of ∼450 fs, which is significantly faster than those of previous Ir(III) complexes with other ligands, is observed only in fac-Ir(ppy)2(ppz) but not in the homoleptic Ir(III) complexes. Such dynamics observed for only heteroleptic Ir(III) complexes must originate from the heteroleptic character, and naturally, the inter-ligand energy transfer between two different types of ligands has been suggested to explain the fast dynamics. Both fs-XTA and TA data, however, favor the assignment of the ultrafast dynamics of ∼450 fs to the internal conversion (IC) process from the ppz-localized 3MLCT to the ppy-localized 3MLCT. The DFT/TDDFT calculations support that the abnormally fast IC for fac-Ir(ppy)2(ppz) is due to a large nonadiabatic coupling and the small energy gap between the two states.

A series of donor–acceptor–donor (D–A–D) pyrene (Py) 2,7-position-based compounds (CN, F, H, Me, and OMe) were designed and synthesized to demonstrate facile intra- and intermolecular charge transfer control by an electron push–pull effect for an efficient mechanofluorochromic (MFC) material. An examination of the photophysical properties of CN–OMe revealed that the locally excited (LE) and intramolecular charge transfer (ICT) state of the compounds were modulated finely by the electron push–pull substituent effect. In addition, it is noteworthy that the CN emission originated only from the LE state despite the D–A–D molecular system. Moreover, we confirmed that the selective LE and/or ICT state modulation affects intra- and intermolecular charge transfer control in the solid-state emission. In particular, this intra- and intermolecular charge transfer control is directly dominated by MFC phenomena, which means that the molecular electron push–pull substituent effect is dependent on MFC behavior. As a result, this study shows that as the electron-withdrawing group ability increases, the intramolecular interactions become insufficient and induce strong intermolecular D–A interactions for stabilizing molecules, leading to high MFC efficiency that is reversibly repeated several times.

A series of meta-terphenyl linked donor–π–acceptor (D–π–A) dyads were prepared to understand the electronic effects of a meta-terphenyl linker according to the electron-accepting ability change. The energy band gaps of the dyads were controlled by tuning the accepting ability, which resulted in emission colors ranging from blue-green to red. In the Lippert–Mataga plots, intramolecular charge transfer (ICT) behavior was observed, which showed gradually increased ICT characteristics as the accepting ability was increased. On the other hand, in the absorption spectra, a red shift of the ICT transition was observed differently from the electron-accepting ability tendency. Thus, the experimental results show that the ICT is determined by steric hindrance rather than the acceptor ability in the ground state due to the lack of π-conjugation of the terphenyl linker by the electron node in the meta-position, whereas ICT in the excited state is controlled by electron-accepting ability.

Knowledge about factors that govern chemoselectivity is pivotal to the design of reactions that are utilized to produce complex organic substances. In the current study, SET-promoted photoaddition ...

Field effect transistor (FET) biosensor is based on metal oxide field effect transistor that is gated by changes in the surface charges induced the reaction of biomolecules. In most cases of FET biosensor, FET biosensor is not being reused after the reaction; therefore, it is an important concept of investigate the biosensor with simplicity, cheap and reusability. However, the conventional cardiac troponin I (cTnI) sensing technique is inadequate owing to its low sensitivity and high operational time and cost. In this study, we developed a rapid and low-cost, and disposable electrical sensor using an extended gate field-effect transistor (EGFET) to detect cTnI, as a key biomarker for myocardiac infarction. We first investigated pH sensing characteristics according to the pH level, which provided a logarithmically linear sensitivity in the pH sensing buffer solution of approximately 57.9 mV/pH. Subsequently, we prepared a cTnI sample and monitored the reaction between cTnI and cTnI antibodies through the changes in the drain current and transfer curves. Our results showed that the EGFET biosensor could successfully detect the cTnI levels as well as the pH with low-cost and rapid detection.

Various covalently linked dimers (CLDs) and their structural isomers have attracted much attention as a potential material to improve the power conversion efficiencies of photovoltaic devices and OLEDs through singlet fission (SF). However, the effect of the molecular configuration on improving the efficiency through the spatial arrangement has not been explored yet. Here, we designed and synthesized two covalently ortho-linked pyrene (Py) dimers, anti- and syn-1,2-di(pyrenyl)benzene (Anti-DPyB and Syn-DPyB), to elucidate the effect of the molecular configuration on SF dynamics. Both Anti-DPyB and Syn-DPyB, which have different Py-stacking configurations, form excimers and then relax to the correlated triplet pair (1(T1T1)) state, indicating the occurrence of SF. Unlike previous studies where the excimer formation inhibited an SF process, the 1(T1T1)’s of Anti-DPyB and Syn-DPyB are formed through the excimer state. The 1(T1T1) of Anti-DPyB dissociates to form free triplets, completing SF, whereas the 1(T1T1) of Syn-DPyB does not undergo dissociation. Our results showcase that the molecular configuration of a CLD plays an important role in SF dynamics, suggesting that the strategic molecular design and its experimental characterization may provide a new route to improving the power conversion efficiency in real devices.

Excited-state intramolecular proton transfer (ESIPT) is a fundamental ultrafast photochemical process. Although it has been intensively studied for the development of novel photonic devices such as...

A series of perylene-based donor–acceptor–donor (D–A–D) compounds, 3,9-bis(p-(R)-diphenylamino)perylene (R: CN (2a), F (2b), H (2c), Me (2d), and OMe (2e)), was synthesized using 3,9-dibromoperylen...

A study was conducted to gain insight into the preparative potential of photosensitized reactions of acyclic N-benzylglycinates containing an α-trimethylsilyl group with dimethyl acetylenedicarboxylate (DMAD). The photosensitizers employed in the reactions include 9,10-dicyanoanthracene (DCA), 1,4-dicyanonaphthalene (DCN), rose bengal (RB) and fullerene C60. The results show that photoirradiation of oxygenated solutions containing the photosensitizers, glycinates and dimethyl acetylenedicarboxylate leads to competitive formation of pyrroles and β-enamino-esters. The distributions of pyrrole and β-enamino-ester products formed in these reactions are highly influenced by the electronic nature of the phenyl ring substituent on the benzylglycinates and the photosensitizer used. These photoaddition reactions take place via mechanistic pathways involving competitive formation of azomethine ylides and secondary amines, generated by a mechanistic routes involving initial SET from the benzylglycinates to photosensitizers.

Charge transfer (CT) from electron donor (D) to acceptor (A) plays an important role in photoelectric or electrochemical devices and is a useful concept for a molecule with D and A well distinguishable. Here, we report our finding that even in a molecule with D and A not resolvable, CT can be induced by electronic state mixing (ESM) in a symmetric multi-chromophore system (MCS), namely 1,4-di(1-pyrenyl)benzene (Py-Benz-Py). Unlike Py and Py-Benz, Py-Benz-Py exhibits unique photophysical properties attributable to the reduction of the energy gap between two electronic states induced by ESM. The ESM for Py-Benz-Py is due to the extended π-conjugation owing to the further introduction of Py into Py-Benz, and consequently leads to the favorable intramolecular CT, followed by the planarization due to the twisting motion between Py and phenyl moieties. Time-resolved spectroscopic data demonstrate that the twisting process of the Py moiety in acetonitrile occurs with two unequal time constants, suggesting the localized CT state and the asynchronous twisting dynamics of two Py moieties unlike the delocalized CT state in nonpolar and low-polarity solvents leading to the synchronous twisting of two Py moieties. This means that the symmetry-breaking CT in MCSs can induce an asynchronous twisting motion. The results reported here support that a molecule without CT can be turned into another molecule with CT induced by ESM and demonstrate that the excited-state relaxation dynamics can be regulated through the ESM induced by introducing the substituents or changing the environmental factors such as solvent polarities.

A series of asymmetric donor-acceptor (D-A) perylene-based compounds, 3-(N,N-bis(4'-(R)-phenyl)amino)perylene (Peri-DPA(R)), were successfully prepared to explore their intramolecular charge transfer (ICT) properties. To induce ICT between the donor and acceptor, diphenylamine (DPA) derivatives (electron donor units) with the same functional groups (R = CN, F, H, Me, or OMe) at both para positions were linked to the C-3 position of perylene to produce five Peri-DPA derivatives. A steady-state spectroscopy study on Peri-DPA(R)s exhibited a progressively regulated ICT trend consistent with the substituent effect as it progressed from the electron-withdrawing group to the electron-donating group. In particular, a comparative study using a D-A-D (donor-acceptor-donor) system demonstrated that not only the electron push-pull substituent effect but also subunit combinations influence photophysical and electrochemical properties. The different ICT characters observed in Lippert-Mataga plots of D-A(CN) and D-A-D(CN) (CN-substituted D-A and D-A-D) led to the investigation on whether ICT emission of two systems with differences in subunit combinations is of the same type or of a different type. The femtosecond transient absorption (fs-TA) spectroscopic results provided direct evidence of ICT origin and confirmed that D-A(CN) and D-A-D(CN) exhibited the same transition mix of ICT (from donor to acceptor) and reverse ICT (rICT, from arylamine to CN unit). Density functional theory (DFT)/TD-DFT calculations support the presence of ICT for all five compounds, and the experimental observations of rICT presented only for CN-substituted compounds.

Knowledge about factors that govern chemoselectivity is pivotal to the design of reactions that are utilized to produce complex organic substances. In the current study, single-electron transfer (SET)-promoted photoaddition reactions of fullerene C

Microvesicles and exosomes are small membranous vesicles released to the extracellular environment and circulated throughout the body. Because they contain various parental cell-derived biomolecules such as DNA, mRNA, miRNA, proteins, and lipids, their enrichment and isolation are critical steps for their exploitation as potential biomarkers for clinical applications. However, conventional isolation methods (e.g., ultracentrifugation) cause significant loss and damage to microvesicles and exosomes. These methods also require multiple repetitive steps of ultracentrifugation, loading, and wasting of reagents. This article describes a detailed method to fabricate an origami-paper-based device (Exo-PAD) designed for the effective enrichment and isolation of microvesicles and exosomes in a simple manner. The unique design of the Exo-PAD, consisting of accordion-like multifolded layers with convergent sample areas, is integrated with the ion concentration polarization technique, thereby enabling fivefold enrichment of the microvesicles and exosomes on specific layers. In addition, the enriched microvesicles and exosomes are isolated by simply unfolding the Exo-PAD.

The molecular geometry effects of ortho, meta, and para-terphenyl based donor–π–acceptor (D–π–A) dyads on intramolecular charge transfer (ICT) were studied to investigate structure-ICT relationships. Terphenyl based D–π–A dyads were prepared by two-step palladium catalyzed, Suzuki–Miyaura coupling reactions, in which triphenylamine (TPA) was used as the electron donor and 1,2-diphenyl-benzimidazole (IMI) as the electron acceptor. The photophysical and electrochemical properties of terphenyl backbone-based ortho (O), meta (M), and para (P) dyads were compared. In steady state absorption spectra, a red-shift of CT band was observed in the order O < M < P, which was attributed to terphenyl isomer conjugation effects and agreed well with density functional theory (DFT) based calculations. In particular, the emission spectra of the three terphenyl D–π–A dyads produced showed similar emission maxima at ∼475 nm and a bathochromic shift property was observed in order to increase the solvent polarity, indicating the ICT process. From Lippert–Mataga plots, excited-state dipole moment changes (Δμ) were estimated to be 31.5 Debye (D) for O, 62.9 D for M, and 51.5 D for P. For M isomer, a large Δμ and the markedly reduced quantum yield was shown, as well as photo-induced electron transfer (PET) was expected in the excited state, but no radical species were observed by femtosecond transient absorption (TA) measurements. Based on experimental results, we conclude that all three terphenyl based D–π–A dyads, including non-conjugated ortho- and meta-terphenyl dyads, exhibit partial charge transfer rather than unit-electron transfer.

We have successfully prepared a series of pyrene based donor-acceptor-donor (D-A-D) molecules, 1,6-bis[(N,N-p-(R)-diphenylamino)phenyl]pyrene (R = CN (Py-CN), F (Py-F), H (Py-H), Me (Py-Me), and OMe (Py-OMe)), containing N,N-bis(p-(R)-phenyl)aniline as an electron donor and pyrene as an electron acceptor by using the Suzuki-Miyaura cross-coupling reaction in good yield and fully characterized. By introducing various N,N-bis(p-(R)-phenyl)aniline derivatives with electron-donating or electron-withdrawing R groups, the energy band gaps of Py-R were systematically controlled and emission colors were efficiently tuned from blue to yellow (441–536 nm). Absorption spectra of all Py-R compounds showed intramolecular charge transfer (ICT) transitions in the range of 350–450 nm in the ground state. Solvent-dependent emission spectra confirmed the substituent dependence of charge transfer ability in the excited state. Then, the charge transfer tendencies by the substituents were quantitatively observed using the Lippert-Mataga equation. The HOMO and LUMO energy levels of synthesized Py-R compounds were found in the range of −5.44 to −5.97 eV and −2.68 to −2.97 eV respectively from cyclic voltammetry (CV) experimental. Theoretical studies were conducted using density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations to provide a basis for interpreting experimental data. Experimental and calculated values were found to be well correlated with the Hammett constants (σpara) and confirmed that the energy band gap was systematically controlled by the substituent effect. Furthermore, pyrene based D-A-D compounds with controllable band gap were employed as selective chemosensors to detect nitro explosives, and especially Py-CN demonstrated efficient sensing ability for ortho-nitroaniline (o-NA) by fluorescence quenching strategy.

Visible-light-driven water splitting was investigated in a dye sensitized photoelectrosynthesis cell (DSPEC) based on a photoanode with a phosphonic acid-derivatized donor−π–acceptor (D−π–A) organic chromophore, 1, and the water oxidation catalyst [Ru(bda)(4-O(CH2)3P(O3H2)2-pyr)2], 2, (pyr = pyridine; bda = 2,2′-bipyridine-6,6′-dicarboxylate). The photoanode was prepared by using a layering strategy beginning with the organic dye anchored to an FTO|core/shell electrode, atomic layer deposition (ALD) of a thin layer (

Here, the application of the fluorinated polymer [Dupont AF, a copolymer of 4,5-difluoro-2,2-bis(trifluoromethyl)-1,3-dioxole and tetrafluoroethylene] is described in stabilizing phosphonate-derivatized molecular assemblies on oxide electrodes. In the procedure, the polymer was dip-coated onto the surfaces of oxide electrodes with pre-bound, phosphonate-derivatized chromophores and assemblies, including assemblies for water oxidation. The results of the experiments showed a high degree of stabilization by the added polymer and a demonstration of its use in stabilizing surface-bound assemblies for water-oxidation catalysis.

We report on the synthesis and photophysical properties of a photocathode consisting of a molecular bilayer structure self-assembled on p-type NiO nanostructured films. The resulting photocathode and its nanostructured indium–tin oxide analog absorb visible light and convert it into injected holes with injection yields of ∼30%, measured at the first observation time by nanosecond transient absorption spectroscopy, and long-lived reducing equivalents that last for several milliseconds without applied bias. An initial quantum yield of 15% was achieved for photogeneration of the reduced dye on the p-NiO electrode. Nanosecond transient absorption experiments and detailed analyses of the underlying electron transfer steps demonstrate that the overall efficiency of the cell is limited by hole injection and charge recombination processes. Compared with the highly doped indium–tin oxide photocathode, the NiO photocathode shows superior photoconversion efficiencies for generating reducing equivalents and longer li...

Pharmacogenetic testing for clinical applications is steadily increasing. Correct and adequate use of pharmacogenetic tests is important to reduce unnecessary medical costs and adverse patient outcomes. This document contains recommended pharmacogenetic testing guidelines for clinical application, interpretation, and result reporting through a literature review and evidence-based expert opinions for the clinical pharmacogenetic testing covered by public medical insurance in Korea. This document aims to improve the utility of pharmacogenetic testing in routine clinical settings.

A series of perylene-based donor-acceptor-donor (D-A-D) compounds, 3,9-bis(

Tandem junction photoelectrochemical water-splitting devices, whereby two light absorbing electrodes targeting separate portions of the solar spectrum generate the voltage required to convert water to oxygen and hydrogen, enable much higher possible efficiencies than single absorber systems. We report here on the development of a tandem system consisting of a dye-sensitized photoelectrochemical cell (DSPEC) wired in series with a dye-sensitized solar cell (DSC). The DSPEC photoanode incorporates a tris(bipyridine)ruthenium(II)-type chromophore and molecular ruthenium based water oxidation catalyst. The DSPEC was tested with two more-red absorbing DSC variations, one utilizing N719 dye with an I3–/I– redox mediator solution and the other D35 dye with a tris(bipyridine)cobalt ([Co(bpy)3]3+/2+) based mediator. The tandem configuration consisting of the DSPEC and D35/[Co(bpy)3]3+/2+ based DSC gave the best overall performance and demonstrated the production of H2 from H2O with the only energy input from simul...

This study aimed to compare the quality characteristics of developed rice Jochung (E) with those of commercial-rice Jochung (A, B, C, and D). The total soluble solid, reducing sugar, and dextrose equivalent of developed rice Jochung were 80 °Brix, 44.53%, and 56.94%, respectively. The pH and titrable acidity were 6.25 and 0.19%, respectively. The color difference value (ΔE) of developed rice Jochung was 74.42, which was significantly lower than the other samples investigated. The light transmittance and total polyphenol contents of developed rice Jochung were 56.4%T and 108.23 mg GAE/100 g, respectively. The adhesiveness values of various commercial-rice Jochung products were 29.0~66.0 sec, while that of developed-rice Jochung was 61 sec, showing good textural properties for use in manufacturing Hangwa, a Korean traditional cookie. The electron-donating values of various rice Jochung were 20.4~50.3%, among which the developed-rice Jochung showed the highest value. The reducing powers of various rice Jochung products were 0.44~0.72, while that of the developed product was 0.72, which was significantly higher than the other values. Sensory evaluation revealed that the color scores of developed- and commercial-rice Jochung products were 6.70~6.80. Flavor scores of rice Jochung products ranged from 6.00 to 7.00. Taste and mouth feeling scores of developed-rice Jochung did not significantly differ from those of commercial Jochung products. Compared to commercial-rice Jochung products, developed-rice Jochung made with malt extract exhibited high polyphenols content. However, there were no significant differences in the overall acceptability scores between commercial-rice Jochung products and the developed product. The developed-rice Jochung analyzed in this study may be useful as a traditional sweetener for various Hangwa products as a substitute for corn syrup or Jochung.

Layer-by-Layer (LbL) polyelectrolyte self-assembly occurs by the alternate exposure of a substrate to solutions of oppositely charged polyelectrolytes or polyions. Here, we report the application of LbL to construct chromophore–catalyst assemblies consisting of a cationic polystyrene-based Ru polychromophore (PS-Ru) and a [Ru(tpy)(2-pyridyl-N-methylbenzimidazole) (OH2)]2+ water oxidation catalyst (RuC), codeposited with poly(acrylic acid) (PAA) as an inert polyanion. These assemblies are deposited onto planar indium tin oxide (ITO, Sn:In2O3) substrates for electrochemical characterization and onto mesoporous substrates consisting of a SnO2/TiO2 core/shell structure atop fluorine doped tin oxide (FTO) for application to light-driven water oxidation in a dye-sensitized photoelectrosynthesis cell. Cyclic voltammetry and ultraviolet–visible absorption spectroscopy reveal that multilayer deposition progressively increases the film thickness on ITO glass substrates. Under an applied bias, photocurrent measureme...

The achievement of long-lived photoinduced redox separation lifetimes has long been a central goal of molecular-based solar energy conversion strategies. The longer the redox-separation lifetime, the more time available for useful work to be extracted from the absorbed photon energy. Here we describe a novel strategy for dye-sensitized solar energy applications in which redox-separated lifetimes on the order of milliseconds to seconds can be achieved based on a simple toolkit of molecular components. Specifically, molecular chromophores (C), electron acceptors (A) and electron donors (D) were self-assembled on the surfaces of mesoporous, transparent conducting indium tin oxide nanoparticle (nanoITO) electrodes to prepare both photoanode (nanoITO|-A-C-D) and photocathode (nanoITO|-D-C-A) assemblies. Nanosecond transient-absorption and steady-state photolysis measurements show that the electrodes function microscopically as molecular analogues of semiconductor p/n junctions. These results point to a new chemical strategy for dye-sensitized solar energy conversion based on molecular excited states and electron acceptors/donors on the surfaces of transparent conducting oxide nanoparticle electrodes.

To gain new insights into ligand-to-ligand charge-transfer (LLCT) dynamics, we synthesised two heteroleptic Ir(3+) complexes: (Ir(dfppy)2(tpphz)) and (Ir(dfppy)2(dpq)), where dfppy, tpphz, and dpq are 2-(4,6-difluorophenyl)pyridine, tetrapyrido[3,2-a:2',3'-c:3'',2''-h:2''',3'''-j]phenazine, and 2,3-bis-(2-pyridyl)-quinoxaline, respectively. The tpphz and dpq ligands have longer π-conjugation than dfppy. Therefore, the excited ligand-centred (LC) state and the metal-to-ligand charge transfer (MLCT) state of dfppy are higher than those of tpphz and dpq. The LLCT dynamics from dfppy to tpphz (or dpq) was probed using femtoscond transient absorption (TA) spectroscopy after the selective excitation of dfppy. The TA band for the LC/MLCT state of dfppy is observed at 480 nm. Because of the LLCT process, the TA bands related to the MLCT states of tpphz and dpq ligands increased, whereas those of dfppy decreased. The time constants for the LLCT process were 17 ps for Ir(dfppy)2(tpphz) and 5 ps for Ir(dfppy)2(dpq). The MLCT emission of Ir(dfppy)2(tpphz) showed strong temperature dependence, indicating that the LLCT process has a significant energy barrier. In comparison, the temperature weakly influenced the emission of Ir(dfppy)2(dpq), and thus, its LLCT process may have a smaller barrier. The anomalous rigidochromism and photodynamic behaviours can be explained in terms of the barrier between cyclometalating and ancillary ligands.

Visible light driven water splitting in a dye-sensitized photoelectrochemical cell (DSPEC) based on a phosphonic acid-derivatized donor–π–acceptor (D–π–A) organic dye (P–A–π–D) is described with the dye anchored to an FTO|SnO2/TiO2 core/shell photoanode in a pH 7 phosphate buffer solution. Transient absorption measurements on FTO|TiO2|–[P–A–π–D] compared to core/shell, FTO|SnO2/TiO2(3 nm)|–[P–A–π–D], reveal that excitation of the dye is rapid and efficient with a decrease in back electron rate by a factor of ∼10 on the core/shell. Upon visible, 1 sun excitation (100 mW cm−2) of FTO|SnO2/TiO2(3 nm)|–[P–A–π–D] in a phosphate buffer at pH 7 with 20 mM added hydroquinone (H2Q), photocurrents of ∼2.5 mA cm−2 are observed which are sustained over >15 min photolysis periods with a current enhancement of ∼30-fold compared to FTO|TiO2|–[P–A–π–D] due to the core/shell effect. On surfaces co-loaded with both –[P–A–π–D] and the known water oxidation catalyst, Ru(bda)(pyP)2 (pyP = pyridin-4-methyl phosphonic acid), maximum photocurrent levels of 1.4 mA cm−2 were observed which decreased over an 10 min interval to 0.1 mA cm−2. O2 was measured by use of a two-electrode, collector–generator sandwich cell and was produced in low faradaic efficiencies with the majority of the oxidative photocurrent due to oxidative decomposition of the dye.

Anti- and syn-isomers of benzo-1,2-dipyrene were synthesized, and nonidentical experimental absorption spectra were observed. The B3LYP, B3LYP-D3, ωB97XD, and optimally tuned long-range corrected (LC) BOP functionals were assessed. B3LYP and B3LYP-D3 underestimated and ωB97XD overestimated the fundamental gaps and their following optical gaps in both isomers. The LC-BOP functional with the range separation parameter (µ=0.18) using the geometries optimized with LCgau-BOP + LRD reproduced the experimental absorption spectra of both isomers well. Therefore, in the case of the absorption spectrum calculation of the excimer-like isomers, it is significant to include both the weak interaction term and long-range Hartree-Fock exchange interaction appropriately.

A study was conducted to gain insight into the preparative potential of photosensitized reactions of acyclic

An electrochemical procedure for preparing chromophore-catalyst assemblies on oxide electrode surfaces by reductive vinyl coupling is described. On core/shell SnO2/TiO2 nanoparticle oxide films, excitation of the assembly with 1 sun (100 mW cm–2) illumination in 0.1 M H2PO4–/HPO42– at pH 7 with an applied bias of 0.4 V versus SCE leads to water splitting in a DSPEC with a Pt cathode. Over a 5 min photolysis period, the core/shell photoanode produced O2 with a faradaic efficiency of 22%. Instability of the surface bound chromophore in its oxidized state in the phosphate buffer leads to a gradual decrease in photocurrent and to the relatively modest faradaic efficiencies.

The mechanism of electrocatalytic water oxidation by the water oxidation catalyst, ruthenium 2,2′-bipyridine-6,6′-dicarboxylate (bda) bis-isoquinoline (isoq), [Ru(bda)(isoq)2], 1, at metal oxide electrodes has been investigated. At indium-doped tin oxide (ITO), diminished catalytic currents and increased overpotentials are observed compared to glassy carbon (GC). At pH 7.2 in 0.5 M NaClO4, catalytic activity is enhanced by the addition of [Ru(bpy)3]2+ (bpy = bipyridine) as a redox mediator. Enhanced catalytic rates are also observed at ITO electrodes derivatized with the surface-bound phosphonic acid derivative [Ru(4,4′-(PO3H2)2bpy)(bpy)2]2+, RuP2+. Controlled potential electrolysis with measurement of O2 at ITO with and without surface-bound RuP2+ confirm that water oxidation catalysis occurs. Remarkable rate enhancements are observed with added acetate and phosphate, consistent with an important mechanistic role for atom-proton transfer (APT) in the rate-limiting step as described previously at GC elect...

Mesoporous metal oxide film electrodes consisting of derivatized 5.5 μm thick SnO

On the basis of the results of frontier orbital considerations, 4-substituted-2'-pyridyltriazoles were designed to serve as ancillary ligands in 2-phenylpyridine main ligand containing heteroleptic iridium(III) complexes that display deep blue phosphorescence emission. The iridium(III) complexes, Ir1-Ir7, prepared using the new ancillary ligands, were found to display structured, highly quantum efficient (Φp = 0.20-0.42) phosphorescence with emission maxima in the blue to deep blue 448-456 nm at room temperature. In accord with predictions based on frontier orbital considerations, the complexes were observed to have emission properties that are dependent on the electronic nature of substituents at the C-4 position of the pyridine moiety of the ancillary ligand. Importantly, placement of an electron-donating methyl group at C-4' of the pyridine ring of the 5-(pyridine-2'-yl)-3-trifluoromethyl-1,2,4-triazole ancillary ligand leads to an iridium(III) complex that displays a deep blue phosphorescence emission maximum at 448 nm in both the liquid and film states at room temperature. Finally, an OLED device, constructed using an Ir-complex containing the optimized ancillary ligand as the dopant, was found to emit deep blue color with a CIE of 0.15, 0.18, which is close to the perfect goal of 0.15, 0.15.

Nature Chemistry 8, 845–852 (2016); published online 6 June 2016; corrected after print 24 August 2016. In the version of this Article originally published, the affiliation details for Kyung-Ryang Wee were not correct, these have been updated in the online versions of this paper.

The rate of electrocatalytic water oxidation by the heterogeneous water oxidation catalyst [Ru(bda)(4-O(CH2)3P(O3H2)2-pyr)2], 1, (pyr = pyridine; bda = 2,2′-bipyridine-6,6′-dicarboxylate) on metal oxide surfaces is greatly enhanced relative to water as the solvent. In these experiments with propylene carbonate (PC) as the nonaqueous solvent, water is the limiting reagent. Mechanistic studies point to atom proton transfer (APT) as the rate limiting step in water oxidation catalysis.

A series of phosphonate-derivatized, high redox potential porphyrins with mesityl, pentafluorophenyl, and heptafluoropropyl meso-substituents were synthesized by acid-catalyzed condensation reactions. Ground and excited state redox potentials in the series were varied systematically with the electron-donating or electron-accepting nature of the meso-substitutents. The extent of excitation and injection by porphyrin singlet excited states surface-bound to SnO2/TiO2 core/shell metal oxide nanoparticle films varies with the excited state reduction potential, E°(')(P(+)/P*). With the mesityl-substituted porphyrin, high current density and sustained photocurrents are observed at pH 7 with the addition of the electron transfer donor hydroquinone.

Visible-light-driven H(2) evolution based on Dye/TiO(2)/Pt hybrid photocatalysts was investigated for a series of (E)-3-(5'-{4-[bis(4-R(1)-phenyl)amino]phenyl}-4,4'-(R(2))(2)-2,2'-bithiophen-5-yl)-2-cyanoacrylic acid dyes. Efficiencies of hydrogen evolution from aqueous suspensions in the presence of ethylenediaminetetraacetic acid as electron donor under illumination at λ>420 nm were found to considerably depend on the hydrophilic character of R(1), varying in the order MOD (R(1)=CH(3)OCH(2), R(2)=H)≈MO4D (R(1)=R(2)=CH(3)OCH(2))>HD (R(1)=R(2)=H)>PD (R(1)=C(3)H(7), R(2)=H). In the case of MOD/TiO(2)/Pt, the apparent quantum yield for photocatalyzed H(2) generation at 436 nm was 0.27±0.03. Transient absorption measurements for MOD- or PD-grafted transparent films of TiO(2) nanoparticles dipped into water at pH 3 commonly revealed ultrafast formation (

We demonstrate that injection of electrons in 1-bis[4-[N,N-di(4-tolyl)amino]phenyl]-cyclohexane (TAPC) layer irreversibly induces defect sites responsible for “electromer” emission. We also show that the defects alter the charge transporting properties of TAPC layer to influence the charge balance of iridium(III)[bis(4,6-difluorophenyl)pyridinato-N,C 2′ ]tetrakis(1-pyrazolyl)borate (FIr6) based deep blue phosphorescent organic light emitting diodes (PHOLED). The present investigation implies that deep-blue PHOLEDs should be carefully designed for the emission zone to be located far enough from the TAPC layer so as to avoid or minimize the emission from TAPC layer.

probably because the parent carboranes and their derivativeswithout p substituent show little or no absorption at>250 nm, nor any emission. Even for their p-substitutedderivatives,furthermore,nodetailedinvestigationshavebeenperformed, particularly into how the carborane cages affecttheir excited-state behavior.