Nonabelian Hodge theory and vector valued modular forms

We examine the relationship between nonabelian Hodge theory for Riemann surfaces and the theory of vector valued modular forms. In particular, we explain how one might use this relationship to prove a conjectural three-term inequality on the weights of free bases of vector valued modular forms associated to complex, finite dimensional, irreducible representations of the modular group. This conjecture is known for irreducible unitary representations and for all irreducible representations of dimension at most 12. We prove new instances of the three-term inequality for certain nonunitary representations, corresponding to a class of maximally-decomposed variations of Hodge structure, by considering the same inequality with respect to a new type of modular form, called a "Higgs form", that arises naturally on the Dolbeault side of nonabelian Hodge theory. The paper concludes with a discussion of a strategy for reducing the general case of nilpotent Higgs bundles to the case under consideration in our main theorem.Comment: 22 pages, 1 tabl

Solid-state structure and anti­microbial and cytotoxicity studies of a cucurbit[6]uril-like Cu6L4 constructed from 3,5-bis­[(1H-tetra­zol-5-yl)meth­yl]-4H-1,2,4-triazol-4-amine

3,5-Bis[(1H-tetra­zol-5-yl)meth­yl]-4H-1,2,4-triazol-4-amine (H2L) associates under deprotonation with CuSO4 in aqueous medium to form a new waisted barrel-shaped M6L4 cluster, namely hexa­aqua­tetra­kis­{μ4-3,5-bis­[(1H-tetra­zol-5-yl)meth­yl]-4H-1,2,4- triazol-4-amine}-μ4-sulfato-hexa­copper(II) sulfate hydrate, [Cu6(SO4) (C6H6N12)4(H2O)6]SO4·nH2O (n = ∼23) (1). Cluster 1 resembles concave cucurbit[6]uril and has one disordered sulfate anion trapped inside the cage, which additionally stabilizes the Cu6 unit. The CuII ions have either a square-pyramidal or a distorted octa­hedral geometry. The equatorial positions are filled by N atoms from the L2− ligand, while the axial positions are occupied by coordinated water mol­ecules and O atoms of the sulfate counter-ion. In the solid state, the Cu6 clusters are connected through a large number of hydrogen bonds formed by uncoordinated water mol­ecules and an additional sulfate anion. The compound shows good anti­microbial activity against E. coli tested with the Kirby Bauer approach. In addition, the cell viability towards HeLa and L-929 cells was studied

Heptacoordinate Coii complex: a new architecture for photochemical hydrogen production

The first heptacoordinate cobalt catalyst for light-driven hydrogen production in water has been synthesized and characterized. Photochemical experiments using [Ru(bpy)₃]²⁺ as photosensitizer gave a turnover number (TON) of 16300 mol H₂ (mol  cat.)⁻¹ achieved in 2 hours of irradiation with visible (475 nm) light. This promising result provides a path forward in the development of new structures to improve the efficiency of the catalysis

Synthesis of Bioctacene‐Incorporated Nanographene with Near‐Infrared Chiroptical Properties

We report the synthesis of a hexabenzoperihexacene (HBPH) with two incorporated octacene substructures, which was unambiguously characterized by single-crystal X-ray analysis. The theoretical isomerization barrier of the (P,P)-/(P,M)-forms was estimated to be 38.4 kcal mol−1, and resolution was achieved by chiral HPLC. Notably, the enantiomers exhibited opposite circular dichroism responses up to the near-infrared (NIR) region (830 nm) with a high gabs value of 0.017 at 616 nm. Moreover, HBPH demonstrated NIR emission with a maximum at 798 nm and an absolute PLQY of 41 %. The excited-state photophysical properties of HBPH were investigated by ultrafast transient absorption spectroscopy, revealing an intriguing feature that was attributed to the rotational and/or conformational dynamics of HBPH after excitation. These results provide new insight into the design of chiral nanographene with NIR optical properties for potential chiroptical applications.journal articl

Oxygen transfer reactivity mediated by nickel perfluoroalkyl complexes using molecular oxygen as a terminal oxidant

Nickel perfluoroethyl and perfluoropropyl complexes supported by naphthyridine-type ligands show drastically different aerobic reactivity from their trifluoromethyl analogs resulting in facile oxygen transfer to perfluoroalkyl groups or oxygenation of external organic substrates (phosphines, sulfides, alkenes and alcohols) using O2 or air as a terminal oxidant. Such mild aerobic oxygenation occurs through the formation of spectroscopically detected transient high-valent NiIII and structurally characterized mixed-valent NiII–NiIV intermediates and radical intermediates, resembling O2 activation reported for some Pd dialkyl complexes. This reactivity is in contrast with the aerobic oxidation of naphthyridine-based Ni(CF3)2 complexes resulting in the formation of a stable NiIII product, which is attributed to the effect of greater steric congestion imposed by longer perfluoroalkyl chains.journal articl

Efficient perovskite nanocrystal light-emitting diodes using a benzimidazole-substituted anthracene derivative as the electron transport material

Colloidal nanocrystals of organic–inorganic hybrid perovskites (OIHPs) are an emerging class of solid-state lighting materials owing to their outstanding photophysical properties. Considerable research efforts have been devoted to the fabrication of high-performance light-emitting diodes (LEDs) based on these materials, including interface engineering which is essential for balancing the electron and hole injection in devices. Here, we report efficient perovskite nanocrystal LEDs based on a new electron transport material (ETM), 9,10-bis(N-benzimidazolyl)anthracene (BBIA), possessing a high electron mobility of 4.17 × 10−4 cm2 V−1 s−1 at an electric field of 105 V cm−1. Compared to control devices based on the ETM 2,2′,2′′-(1,3,5- benzinetriyl)-tris(1-phenyl-1-H-benzimidazole) (TPBi), BBIA-based devices exhibit a nearly two-fold enhancement, increasing the current and external quantum efficiencies from 6.25 cd A−1 and 1.51% to 12.2 cd A−1 and 2.96%, respectively. In addition, a small degree of efficiency roll-off of 8 ± 1% at a luminance of 2000 cd m−2, as well as a low turn-on voltage of 2.35 V, has been demonstrated. The anthracene-based compounds may open up new research opportunities for interface engineering in perovskite LEDs

Synthesis of Zigzag- and Fjord-Edged Nanographene with Dual Amplified Spontaneous Emission

We report the synthesis of a dibenzodinaphthocoronene (DBDNC) derivative as a novel nanographene with armchair, zigzag, and fjord edges, which was characterized by NMR and X-ray crystallography as well as infrared (IR) and Raman spectroscopies. Ultrafast transient absorption (TA) spectroscopy revealed the presence of stimulated emission signals at 655 nm and 710 nm with a relatively long lifetime, which resulted in dual amplified spontaneous emission (ASE) bands under ns-pulsed excitation, indicating the promise of DBNDC as a near-infrared (NIR) fluorophore for photonics. Our results provide new insight into the design of nanographene with intriguing optical properties by incorporating fjord edges.This work was financially supported by the Okinawa Institute of Science and Technology Graduate University (OIST), the Max Planck Society, JSPS KAKENHI Grant No. JP19K24686, and the European Union’s Horizon 2020 Research and Innovation program under grant agreement no. 101017821 (LIGHT-CAP). G. M. P thanks Fondazione Cariplo (Grant no. 2018-0979) for financial support. Researchers from the University of Alicante acknowledge support from the Spanish Ministerio de Ciencia e Innovación and the European Union (Next Generation EU) through grant no. PID2020-119124RB-I00; and to the Conselleria de Innovación, Universidades y Sociedad Digital de la Comunidad Valenciana (Grant No. AICO/2021/093)

1,3-Diamine-Derived Catalysts: Design, Synthesis, and the Use in Enantioselective Mannich Reactions of Ketones

1,3-Diamine-derived catalysts were designed, synthesized, and used in asymmetric Mannich reactions of ketones. The reactions catalyzed by one of the 1,3-diamine derivatives in the presence of acids afforded the Mannich products with high enantioselectivities under mild conditions. In most cases, bond formation occurred at the less-substituted α-position of the ketone carbonyl group. Our results indicate that the primary and the tertiary amines of the 1,3-diamine derivative cooperatively act for the catalysis