Photodriven electron-transfer dynamics in a series of heteroleptic Cu(I)-anthraquinone dyads.

Solar fuels catalysis is a promising route to efficiently harvesting, storing, and utilizing abundant solar energy. To achieve this promise, however, molecular systems must be designed with sustainable components that can balance numerous photophysical and chemical processes. To that end, we report on the structural and photophysical characterization of a series of Cu(I)-anthraquinone-based electron donor-acceptor dyads. The dyads utilized a heteroleptic Cu(I) bis-diimine architecture with a copper(I) bis-phenanthroline chromophore donor and anthraquinone electron acceptor. We characterized the structures of the complexes using x-ray crystallography and density functional theory calculations and the photophysical properties via resonance Raman and optical transient absorption spectroscopy. The calculations and resonance Raman spectroscopy revealed that excitation of the Cu(I) metal-to-ligand charge-transfer (MLCT) transition transfers the electron to a delocalized ligand orbital. The optical transient absorption spectroscopy demonstrated that each dyad formed the oxidized copper-reduced anthraquinone charge-separated state. Unlike most Cu(I) bis-phenanthroline complexes where increasingly bulky substituents on the phenanthroline ligands lead to longer MLCT excited-state lifetimes, here, we observe a decrease in the long-lived charge-separated state lifetime with increasing steric bulk. The charge-separated state lifetimes were best explained in the context of electron-transfer theory rather than with the energy gap law, which is typical for MLCT excited states, despite the complete conjugation between the phenanthroline and anthraquinone moieties.

Site-specific electronic structure of covalently linked bimetallic dyads from nitrogen K-edge x-ray absorption spectroscopy.

A nitrogen K-edge x-ray absorption near-edge structure (XANES) survey is presented for tetrapyrido[3,2-a:2',3'-c:3″,2″-h:2‴,3‴-j]phenazine (tpphz)-bridged bimetallic assemblies that couple chromophore and catalyst transition metal complexes for light driven catalysis, as well as their individual molecular constituents. We demonstrate the high N site sensitivity of the N pre-edge XANES features, which are energetically well-separated for the phenazine bridge N atoms and for the individual metal-bound N atoms of the inner coordination sphere ligands. By comparison with the time-dependent density functional theory calculated spectra, we determine the origins of these distinguishable spectral features. We find that metal coordination generates large shifts toward higher energy for the metal-bound N atoms, with increasing shift for 3d < 4d < 5d metal bonding. This is attributed to increasing ligand-to-metal σ donation that increases the effective charge of the bound N atoms and stabilizes the N 1s core electrons. In contrast, the phenazine bridge N pre-edge peak is found at a lower energy due to stabilization of the low energy electron accepting orbital localized on the phenazine motif. While no sensitivity to ground state electronic coupling between the individual molecular subunits was observed, the spectra are sensitive to structural distortions of the tpphz bridge. These results demonstrate N K-edge XANES as a local probe of electronic structure in large bridging ligand motifs, able to distinctly investigate the ligand-centered orbitals involved in metal-to-ligand and ligand-to-ligand electron transfer following light absorption.

Optical detection of alcohols with a Cu(I)HETPHEN complex by reversible aldehyde to hemiacetal conversion.

A heteroleptic copper(I) bis(phenanthroline) complex with aldehyde groups at the 4,7 positions of the phenanthroline ligand was synthesized. The complex is responsive to alcohol, resulting in a distinct colour change caused by the facile reaction of the aldehyde group with alcohol, forming a hemiacetal product. The aldehyde species can be regenerated after heating the intermediate at 80 °C for 10 minutes, demonstrating the reusability of the complex for alcohol detection. This work presents a new strategy for applying transition metal complexes in small molecule sensing by installing functional groups in the secondary coordination sphere which reversibly react with analytes.

Changing Directions: Influence of Ligand Electronics on the Directionality and Kinetics of Photoinduced Charge Transfer in Cu(I)Diimine Complexes.

A key challenge to the effective utilization of solar energy is to promote efficient photoinduced charge transfer, specifically avoiding unproductive, circuitous electron-transfer pathways and optimizing the kinetics of charge separation and recombination. We hypothesize that one way to address this challenge is to develop a fundamental understanding of how to initiate and control directional photoinduced charge transfer, particularly for earth-abundant first-row transition-metal coordination complexes, which typically suffer from relatively short excited-state lifetimes. Here, we report a series of functionalized heteroleptic copper(I)bis(phenanthroline) complexes, which have allowed us to investigate the directionality of intramolecular photoinduced metal-to-ligand charge transfer (MLCT) as a function of the substituent Hammett parameter. Ultrafast transient absorption suggests a complicated interplay of MLCT localization and solvent interaction with the Cu(II) center of the MLCT state. This work provides a set of design principles for directional charge transfer in earth-abundant complexes and can be used to efficiently design pathways for connecting the molecular modules to catalysts or electrodes and integration into systems for light-driven catalysis.

Synthesis and Magnetic Properties of Antimony-Ligated Co(II) Complexes: Stibines versus Phosphines.

Herein, we test the hypothesis that neutral, heavy-atom stibine donors can increase the extent of spin-orbit coupling on light, 3d transition metal. To this end, we developed a novel synthetic route toward coordinating a paramagnetic 3d metal ion─cobalt(II)─with neutral stibine ligands. Such complexes have not been reported in the literature due to the weak σ donor strength of stibines and the hard-soft mismatch between a 3d metal and a 5p ligand─which herein has been overcome using alkylated Sb donors. Magnetometry of [(SbiPr2Ph)2Co(I)2] (1) reveals that the stibine complex 1 exhibits a higher magnitude D value (D = |24.96| cm-1) than the spectroscopically derived value for the corresponding phosphine complex 3 (D = -13.13 cm-1), indicative of large zero-field splitting. CASSCF/NEVPT2 calculations corroborate the experimental D values for 1 and 3, predicting D = -31.9 and -8.9 cm-1, respectively. A re-examination of magnetic parameters across the entire series [(ER3)2Co(X)2] (E = P → Sb; X = Cl → I) reveals that (i) increasingly heavy pnictogens lead to an increased X-Co-X bond angle, which is correlated with larger magnitude D values, and (ii) for a given X-Co-X bond angle, the D value is always higher in the presence of a heavy pnictogen as compared with a heavy halide. Ab initio ligand field theory calculations for 1 (stibine complex) and 3 (phosphine complex) reveal no substantial differences in spin-orbit coupling (ζ = 479.2, 480.2 cm-1) or Racah parameter (B = 947.5, 943.9 cm-1), an indicator of covalency. Thus, some "heavy atom effect" on the D value beyond geometric perturbation is operative, but its precise mechanism(s) of action remains obscure.

Bimetallic Copper/Ruthenium/Osmium Complexes: Observation of Conformational Differences Between the Solution Phase and Solid State by Atomic Pair Distribution Function Analysis.

High-energy X-ray scattering and pair distribution function analysis (HEXS/PDF) is a powerful method to reveal the structure of materials lacking long-range order, but is underutilized for molecular complexes in solution. We demonstrate the application of HEXS/PDF with 0.26 Šresolution to uncover the solution structure of five bimetallic CuI /RuII /OsII complexes. HEXS/PDF of each complex in acetonitrile solution confirms the pairwise distances in the local coordination sphere of each metal center as well as the metal⋅⋅⋅metal distances separated by over 12 Å. The metal⋅⋅⋅metal distance detected in solution is compared with that from the crystal structure and molecular models to confirm that distortions to the metal bridging ligand are unique to the solid state. This work presents the first example of observing sub-Ångström conformational differences by direct comparison of solution phase and solid-state structures and shows the potential for HEXS/PDF in the determination of solution structure of single molecules.

Overexpressing a NPR1-like gene from Citrus paradisi enhanced Huanglongbing resistance in C. sinensis.

KEY MESSAGE: Overexpression of CiNPR4 enhanced resistance of transgenic citrus plants to Huanglongbing by perceiving the salicylic acid and jasmonic acid signals and up-regulating the transcriptional activities of plant-pathogen interaction genes. Developing transgenic citrus plants with enhanced immunity is an efficient strategy to control citrus Huanglongbing (HLB). Here, a nonexpressor of pathogenesis-related gene 1 (NPR1) like gene from HLB-tolerant 'Jackson' grapefruit (Citrus paradisi Macf.), CiNPR4, was introduced into 'Wanjincheng' orange (Citrus sinensis Obseck). CiNPR4 expression was determined in transgenic citrus plants using quantitative real-time PCR analyses. The Candidatus Liberibacter asiaticus (CLas) pathogen of HLB was successfully transmitted to transgenic citrus plants by grafting infected buds. HLB symptoms developed in transgenic and wild-type (WT) plants by 9 months after inoculation. A CLas population analysis showed that 26.9% of transgenic lines exhibited significantly lower CLas titer levels compared with the CLas-infected WT plants at 21 months after inoculation. Lower starch contents and anatomical aberration levels in the phloem were observed in transgenic lines having enhanced resistance compared with CLas-infected WT plants. CiNPR4 overexpression changed the jasmonic acid, but not salicylic acid, level. Additionally, the jasmonic acid and salicylic acid levels increased after CLas infection. Transcriptome analyses revealed that the enhanced resistance of transgenic plants to HLB resulted from the up-regulated transcriptional activities of plant-pathogen interaction-related genes.

Associations between optic disc characteristics and macular choroidal microvasculature in young patients with high myopia.

BACKGROUND: This study aimed to examine changes to optic disc characteristics and macular choroidal microvasculature, and their relationships in young patients with high myopia (HM). METHODS: A total of 90 patients were enrolled in this cross-sectional study. Based on their refractive power, the patients were divided into three groups: 27 in the control group, 34 in the HM group and 29 in the extremely high myopia group. Images of each patient's macula and optic disc were taken by ocular coherence tomography angiography. The macular choroidal and retinal thickness, capillary vessel density and capillary flow area were measured using Matlab software. Parapapillary atrophy (PPA) and the ovality index (OI) obtained from the scanning laser ophthalmoscopy images and the degree of optic disc tilt obtained from the optic nerve head ocular coherence tomography B-scans were analysed by Image J and Matlab software. RESULTS: The PPA area, OI and degree of optic disc tilt were significantly different among the three groups (all p ≤ 0.001). The macular choroidal thickness and microvasculature were significantly different among the three groups (all p < 0.05). Macular choroidal thickness was significantly correlated with PPA area and the degree of optic disc tilt (r = -0.331, p = 0.003; r = -0.394, p = 0.001, respectively). Macular choroidal capillary vessel density and choriocapillaris flow area were associated with PPA area (r = -0.251, p = 0.047; r = -0.326, p = 0.009, respectively). CONCLUSIONS: PPA area, OI and the degree of optic disc tilt were increased in patients with HM, and these changes were correlated with macular choroidal thickness and choroidal microvasculature.

Bioinspired CNP Iron(II) Pincers Relevant to [Fe]-Hydrogenase (Hmd): Effect of Dicarbonyl versus Monocarbonyl Motifs in H2 Activation and Transfer Hydrogenation.

A set of bioinspired carbamoyl CNP pincer complexes are reported that are relevant to [Fe]-hydrogenase (Hmd). The dicarbonyl species [(CNHNNHPR2)Fe(CO)2I] [R = Ph, 1; R = iPr, 2] undergoes ligand deprotonation, resulting in the dearomatized complexes of formulas [(CNHNN=PR2)Fe(CO)2] (5 and 6). The crystal structure and 1H{31P} NMR spectroscopy of the iodide-bound dearomatized species [Na(18-crown-6)][(CNHNN=PPh2)Fe(CO)2I] (7) showed that the deprotonated moiety was the phosphoramine N(H) linkage. Separately, the monocarbonyl complexes [(CNHNNHPR2)Fe(CO)(MeCN)2](BF4) (8 and 9) synthesized, as well as deprotonated and dearomatized in similar fashion. Reactivity studies revealed that the parent dicarbonyl complexes require more forceful conditions for H2 activation, compared with the monocarbonyl complexes. The ligand backbone was not found to participate in H2 activation and H2 → hydride transfer to an organic substrate was not observed in either case. Density functional theory calculations revealed that the higher reactivity of the monocarbonyl complex in H2 splitting could be attributed to its higher affinity for H2. This behavior is attributed to two key points related to the requisite dπ(Fe) → σ*(H2) back-bonding interaction in a conventional M-H2 Kubas interaction: (i) generally, the weaker π donor capacity of the dicarbonyls, and (ii) specifically, the detrimental effect of a strongly π acidic CO ligand (versus weakly π acidic MeCN ligand) trans to the H2 activation site. The higher reactivity of the monocarbonyl complex is also evidenced by the catalytic transfer hydrogenation by monocarbonyl 8, whereas dicarbonyl 1 was ineffective. Overall, the results suggest that Nature uses the dicarbonyl motif in [Fe]-hydrogenase to diminish the interaction between the Fe center and dihydrogen, thereby preventing premature H2 activation prior to substrate (H4MPT+) binding and any resulting nonspecific hydride transfer reactivity.

Antiepileptic geissoschizine methyl ether is an inhibitor of multiple neuronal channels.

Geissoschizine methyl ether (GM) is an indole alkaloid isolated from Uncaria rhynchophyll (UR) that has been used for the treatment of epilepsy in traditional Chinese medicine. An early study in a glutamate-induced mouse seizure model demonstrated that GM was one of the active ingredients of UR. In this study, electrophysiological technique was used to explore the mechanism underlying the antiepileptic activity of GM. We first showed that GM (1-30 µmol/L) dose-dependently suppressed the spontaneous firing and prolonged the action potential duration in cultured mouse and rat hippocampal neurons. Given the pivotal roles of ion channels in regulating neuronal excitability, we then examined the effects of GM on both voltage-gated and ligand-gated channels in rat hippocampal neurons. We found that GM is an inhibitor of multiple neuronal channels: GM potently inhibited the voltage-gated sodium (NaV), calcium (CaV), and delayed rectifier potassium (IK) currents, and the ligand-gated nicotinic acetylcholine (nACh) currents with IC50 values in the range of 1.3-13.3 µmol/L. In contrast, GM had little effect on the voltage-gated transient outward potassium currents (IA) and four types of ligand-gated channels (γ-amino butyric acid (GABA), N-methyl-D-aspartate (NMDA), α-amino-3-hydroxy-5-methylisoxazole-4-propionate/kainite (AMPA/KA receptors)). The in vivo antiepileptic activity of GM was validated in two electricity-induced seizure models. In the maximal electroshock (MES)-induced mouse seizure model, oral administration of GM (50-100 mg/kg) dose-dependently suppressed generalized tonic-clonic seizures. In 6-Hz-induced mouse seizure model, oral administration of GM (100 mg/kg) reduced treatment-resistant seizures. Thus, we conclude that GM is a promising antiepileptic candidate that inhibits multiple neuronal channels.

Versatile Nickel(II) Scaffolds as Coordination-Induced Spin-State Switches for 19 F Magnetic Resonance-Based Detection.

19 F magnetic resonance (MR) based detection coupled with well-designed inorganic systems shows promise in biological investigations. Two proof-of-concept inorganic probes that exploit a novel mechanism for 19 F MR sensing based on converting from low-spin (S=0) to high-spin (S=1) Ni2+ are reported. Activation of diamagnetic NiL1 and NiL2 by light or ß-galactosidase, respectively, converts them into paramagnetic NiL0 , which displays a single 19 F NMR peak shifted by >35 ppm with accelerated relaxation rates. This spin-state switch is effective for sensing light or enzyme expression in live cells using 19 F MR spectroscopy and imaging that differentiate signals based on chemical shift and relaxation times. This general inorganic scaffold has potential for developing agents that can sense analytes ranging from ions to enzymes, opening up diverse possibilities for 19 F MR based biosensing.

Effects of Thiolate Ligation in Monoiron Hydrogenase (Hmd): Stability of the {Fe(CO)2}2+ Core with NNS Ligands.

In this work, we report the effects of NNS-thiolate ligands and nuclearity (monomer, dimer) on the stability of iron complexes related to the active site of monoiron hydrogenase (Hmd). A thermally stable iron(II) dicarbonyl motif is the core feature of the active site, but the coordination features that lead to this property have not been independently evaluated for their contributions to the {Fe(CO)2}2+ stability. As such, non-bulky and bulky benzothiazoline ligands (thiolate precursors) were synthesized and their iron(II) complexes characterized. The use of non-bulky thiolate ligands and low-temperature crystallizations result in isolation of the dimeric species [(NNS)2Fe2(CO)2(I)2] (1), [(NPhNS)2Fe2(CO)2(I)2] (2), and [(MeNNS)2Fe2(CO)2(I)2] (3), which exhibit dimerization via thiolato (µ2-S)2 bridges. In one particular case (unsubstituted NNS ligand), the pathway of decarbonylation and oxidation from 1 was crystallographically elucidated, via isolation of the half-bis-ligated monocarbonyl dimer [(NNS)3Fe2(CO)]I (4) and the fully decarbonylated and oxidized mononuclear [(NNS)2Fe]I (5). The transformations of dicarbonyl complexes (1, 2, and 3) to monocarbonyl complexes (4, 6, and 7) were monitored by UV/vis, demonstrating that 1 and 3 exhibit longer t1/2 (80 and 75 min, respectively) than 2 (30 min), which is attributed to distortion of the ligand backbone. Density functional theory calculations of isolated complexes and putative intermediates were used to corroborate the experimentally observed IR spectra. Finally, dimerization was prevented using a bulky ligand featuring a 2,6-dimethylphenyl substituent, which affords mononuclear iron dicarbonyl complex, [(NPhNSDMPh)Fe(CO)2Br] (8), identified by IR and NMR spectroscopies. The dicarbonyl complex decomposes to the decarbonylated [(NPhNSDMPh)2Fe] (9) within minutes at room temperature. Overall, the work herein demonstrates that the thiolate moiety does not impart thermal stability to the {Fe(CO)2}2+ unit formed in the active site, further indicating the importance of the organometallic Fe-C(acyl) bond in the enzyme.

Syntheses, Structures, and Characterization of Nickel(II) Stibines: Steric and Electronic Rationale for Metal Deposition.

Reactions of the homoleptic and heteroleptic antimony ligands Sb iPr3, Sb iPr2Ph, SbMe2Ph, and SbMePh2 with NiI2 generate rare NiII stibine complexes in either square planar or trigonal bipyramidal (TBP) geometries, depending on the steric size of the ligands. Tolman electronic parameters were calculated (DFT) for each antimony ligand to provide a tabulated resource for the relative strengths of simple antimony ligands. The electronic absorbance spectra of the square planar complexes exhibit characteristic bands [λmax ≈ 560 nm (17 900 cm-1), ε ≈ 4330 M-1 cm-1] at lower energies compared to the reported phosphine complexes, indicating the weak donor strength of the stibine ligands and resultant low-energy ligand field d→ d transitions. The square planar complex Ni(I)2(Sb iPr3)2 reacts with CO to form the TBP complex Ni(I)2(Sb iPr3)2(CO). Lastly, the complexes were investigated for nickel metal deposition on Si|Cu(100 nm) substrates. The complexes with the strongest donating ligand, Sb iPr3, deposited the purest layer of NiCu alloy according to the balanced reaction Ni(I)2(SbIII iPr3)2 → Ni0 + SbV( iPr3)I2; the iodinated SbV byproduct was unambiguously detected in the supernatant by 1H NMR and mass spectrometry. Complexes with weaker ligands (poor I2 acceptors/scavengers) resulted undesired deposition of iodine and CuI on the surface. This work thus serves as a guide for the design and synthesis of 3 d metal complexes with neutral, heavy main-group donors that are useful for metal deposition applications.

Structures, Interconversions, and Spectroscopy of Iron Carbonyl Clusters with an Interstitial Carbide: Localized Metal Center Reduction by Overall Cluster Oxidation.

The syntheses, interconversions, and spectroscopic properties of a set of iron carbonyl clusters containing an interstitial carbide are reported. This includes the low temperature X-ray structures of the six-iron clusters (Y)2[Fe6(µ6-C)(µ2-CO)4(CO)12] (1a-c; where Y = NMe4, NEt4, PPh4); the five-iron cluster [Fe5(µ5-C)(CO)15] (3); and the novel formulation of the five-iron cluster (NMe4)2[Fe5(µ5-C)(µ2-CO)(CO)13] (4). Also included in this set is the novel charge-neutral cluster, [Fe6(µ6-C)(CO)18] (2), for which we were unable to obtain a crystallographic structure. As synthetic proof for the identity of 2, we performed a closed loop of interconversions within a family of crystallographically defined species (1, 3, and 4): [Fe6]2- → [Fe6]0 → [Fe5]0 → [Fe5]2- → [Fe6]2-. The structural, spectroscopic, and electronic properties of this "missing link" cluster 2 were investigated by IR, Raman, XPS, and Mössbauer spectroscopies-as well as by DFT calculations. A single νCO feature (1965 cm-1) in the IR spectrum of 2, as well as a prominent Raman feature (νsymm = 1550 cm-1), are consistent with the presence of terminal carbonyls and a {(µ6-C)Fe6} arrangement of iron centers around the central carbide. The XPS of 2 exhibits a higher energy Fe 2p3/2 feature (707.4 eV) as compared to that of 1 (705.5 eV), consistent with the two-electron oxidation induced by treatment of 1 with two equivalents of [Fc](PF6) under CO atmosphere (for the two added CO ligands). DFT calculations indicate two axial and four equatorial Fe sites in 1, all of which have the same or similar oxidation states, for example, two Fe(0) and four Fe(+0.5). These assignments are supported by Mössbauer spectra for 1, which exhibit two closely spaced quadrupole doublets with δ = 0.076 and 0.064 mm s-1. The high-field Mössbauer spectrum of 2 (4.2 K) exhibits three prominent quadrupole doublets with δ = -0.18, -0.11, and +0.41 mm s-1. This indicates three pairs of chemically equivalent Fe sites. The first two pairs arise from irons of a similar oxidation state, while the last pair arises from irons in a different oxidation state, indicating a mixed-valent cluster. Variable field Mössbauer spectra for 2 were simulated assuming these two groups and a diamagnetic ground state. Taken together, the Mössbauer results and DFT calculations for 2 indicate two axial Fe(II) sites and four equatorial sites of lower valence, probably Fe(0). In the DFT optimized pentagonal bipyramidal structure for 2, the Fe(II)-Ccarbide distances are compressed (∼1.84 Å), while the Fe(0)-Ccarbide distances are elongated (∼2.05 Å). Analysis of the formulations for 1 (closo-square bipyramid) and 2 (nido-pentagonal bipyramid) is considered in the context of the textbook electron-counting rules of 14n+2 and 14n+4 for closo and nido clusters, respectively. This redox-dependent intracluster disproportionation of Fe oxidation states is concluded to arise from changes in bonding to the central carbide. A similar phenomenon may be promoted by the central carbide of the FeMoco cluster of nitrogenase, which may in turn stimulate N2 reduction.

Iron Hydride Detection and Intramolecular Hydride Transfer in a Synthetic Model of Mono-Iron Hydrogenase with a CNS Chelate.

We report the identification and reactivity of an iron hydride species in a synthetic model complex of monoiron hydrogenase. The hydride complex is derived from a phosphine-free CNS chelate that includes a Fe-C(NH)(═O) bond (carbamoyl) as a mimic of the active site iron acyl. The reaction of [((O═)C(HN)N(py)S(Me))Fe(CO)2(Br)] (1) with NaHBEt3 generates the iron hydride intermediate [((O═)C(HN)N(py)S(Me))Fe(H)(CO)2] (2; δFe-H = -5.08 ppm). Above -40 °C, the hydride species extrudes CH3S(-) via intramolecular hydride transfer, which is stoichiometrically trapped in the structurally characterized dimer µ2-(CH3S)2-[((O═)C(HN)N(Ph))Fe(CO)2]2 (3). Alternately, when activated by base ((t)BuOK), 1 undergoes desulfurization to form a cyclometalated species, [((O═)C(NH)NC(Ph))Fe(CO)2] (5); derivatization of 5 with PPh3 affords the structurally characterized species [((O═)C(NH)NC)Fe(CO)(PPh3)2] (6), indicating complex 6 as the common intermediate along each pathway of desulfurization.

Orientational analysis of atomic pair correlations in nanocrystalline indium oxide thin films.

The application of grazing-incidence total X-ray scattering (GITXS) for pair distribution function (PDF) analysis using >50 keV X-rays from synchrotron light sources has created new opportunities for structural characterization of supported thin films with high resolution. Compared with grazing-incidence wide-angle X-ray scattering, which is only useful for highly ordered materials, GITXS/PDFs expand such analysis to largely disordered or nanostructured materials by examining the atomic pair correlations dependent on the direction relative to the surface of the supporting substrate. A characterization of nanocrystalline In2O3-derived thin films is presented here with in-plane-isotropic and out-of-plane-anisotropic orientational ordering of the atomic structure, each synthesized using different techniques. The atomic orientations of such films are known to vary based on the synthetic conditions. Here, an azimuthal orientational analysis of these films using GITXS with a single incident angle is shown to resolve the markedly different orientations of the atomic structures with respect to the planar support and the different degrees of long-range order, and hence, the terminal surface chemistries. It is anticipated that orientational analysis of GITXS/PDF data will offer opportunities to extend structural analyses of thin films by providing a means to qualitatively determine the major atomic orientation within nanocrystalline and, eventually, non-crystalline films.

Photochemical charge accumulation in a heteroleptic copper(i)-anthraquinone molecular dyad via proton-coupled electron transfer.

Developing efficient photocatalysts that perform multi electron redox reactions is critical to achieving solar energy conversion. One can reach this goal by developing systems which mimic natural photosynthesis and exploit strategies such as proton-coupled electron transfer (PCET) to achieve photochemical charge accumulation. We report herein a heteroleptic Cu(i)bis(phenanthroline) complex, Cu-AnQ, featuring a fused phenazine-anthraquinone moiety that photochemically accumulates two electrons in the anthraquinone unit via PCET. Full spectroscopic and electrochemical analyses allowed us to identify the reduced species and revealed that up to three electrons can be accumulated in the phenazine-anthraquinone ring system under electrochemical conditions. Continuous photolysis of Cu-AnQ in the presence of sacrificial electron donor produced doubly reduced monoprotonated photoproduct confirmed unambiguously by X-ray crystallography. Formation of this photoproduct indicates that a PCET process occurred during illumination and two electrons were accumulated in the system. The role of the heteroleptic Cu(i)bis(phenanthroline) moiety participating in the photochemical charge accumulation as a light absorber was evidenced by comparing the photolysis of Cu-AnQ and the free AnQ ligand with less reductive triethylamine as a sacrificial electron donor, in which photogenerated doubly reduced species was observed with Cu-AnQ, but not with the free ligand. The thermodynamic properties of Cu-AnQ were examined by DFT which mapped the probable reaction pathway for photochemical charge accumulation and the capacity for solar energy stored in the process. This study presents a unique system built on earth-abundant transition metal complex to store electrons, and tune the storage of solar energy by the degree of protonation of the electron acceptor.

One-year myopia control efficacy of cylindrical annular refractive element spectacle lenses.

PURPOSE: To evaluate the 1-year myopia control efficacy of a spectacle lens with annular cylindrical microstructures. METHODS: A total of 118 consecutive eligible children aged 8-12 years with -1.00 D to -4.00 D of spherical component myopia and <1.50 D astigmatism were enrolled between August 2020 and November 2020 at the Eye Hospital of Wenzhou Medical University. Participants were randomly assigned to wear cylindrical annular refractive element (CARE) (n = 61) or single-vision (n = 57) spectacle lenses. Cycloplegic autorefraction (spherical equivalent refraction [SER]) and axial length (AL) were measured at baseline and 6-month intervals. Adaptation and compliance questionnaires were administered during all visits. RESULTS: Among 118 randomized participants, 96 (81.4%) were included in the analyses (mean [SE] age, 10.4 [0.6] years; 49 [51.0%] were female; mean [SE] spherical equivalent refractive error, -2.67 [0.66] D; mean [SE] axial length, 24.75 [0.77] mm). Adjusted 1-year myopia progression was -0.56 D for CARE and -0.71 D for single-vision spectacle lenses. The difference in progression was 0.14 D (95% CI, -0.04 to 0.32) for CARE vs single vision. Adjusted 1-year eye growth was 0.27 mm for CARE and 0.35 mm for single vision. The difference in eye growth was 0.09 mm (95% CI, -0.15 to -0.02) for CARE vs single vision. All groups adapted to their lenses with no reported adverse events, complaints, or discomfort. CONCLUSIONS: Among children with myopia, treatment with cylindrical annular refractive element spectacle lenses significantly reduced the rate of axial elongation over 1 year compared with single-vision spectacle lenses.

Choroidal Circulation in 8- to 30-Year-Old Chinese, Measured by SS-OCT/OCTA: Relations to Age, Axial Length, and Choroidal Thickness.

Purpose: The purpose of this study was to evaluate and explore the determinants of choroidal vascularity and choriocapillaris perfusion in a Chinese population aged 8 to 30 years old. Methods: Three hundred eighty eyes from 380 subjects aged 8 to 30 years were included in this cross-sectional study. Submacular choroidal thickness (ChT), total choroidal area (TCA), luminal area (LA), stromal area (SA), choroidal vascularity index (CVI), and choriocapillaris flow deficit (CcFD) were estimated using images obtained from optical coherence tomography (OCT). Results: In this population, the mean ChT was 260.4 ± 63.3 µm, TCA was 1.56 ± 0.38 mm2, LA was 0.94 ± 0.25 mm2, and SA was 0.62 ± 0.15 mm2. The mean CVI was 60.25 ± 3.21% and CcFD was 11.95 ± 1.98%. Multivariable analyses showed that higher CVI and LA was associated with older age, thicker ChT, and shorter AL; and lower CcFD was associated with shorter AL. However, the associations were not uniformly rectilinear between CcFD and age. Specifically, CcFD was positively associated with age in subjects ≤19 years old and negatively associated with age in subjects >19 years old. Conclusions: Development of the choroidal medium- and large-sized vascular layers and choriocapillaris was different across patients aged 8 to 30 years old. Greater axial length was associated with attenuated choroidal circulation. Choroidal thickness correlated well with choroidal vascularity, but not with choriocapillaris perfusion. Further comprehensive and longitudinal assessment of choroidal vasculature and choriocapillaris perfusion will help greatly to understand the physiological and pathological mechanisms responsible for myopia.