Enhancing Oxygen Evolution Reaction Performance of Metal-Organic Frameworks through Cathode Activation.

Due to their abundant active sites and porous structures, metal-organic frameworks (MOFs) have garnered significant interest as oxygen evolution reaction (OER) electrocatalysts. Nevertheless, the development of MOF s-based electrocatalysts with efficient OER activity and excellent stability simultaneously still face challenges. Herein, a cathodic activation strategy was used to enhance the OER electrocatalytic performance of M-HHTP for the first time, where M refers to Ni, Cu, Co, Fe, while HHTP denotes 2, 3, 6, 7, 10, 11-hexahydroxytriphenylene.

Unlocking Giant Third-Order Optical Nonlinearity in (MA)CuX through Introducing Jahn-Teller Distortion.

Nonlinear absorption coefficient and modulation depth stand as pivotal properties of nonlinear optical (NLO) materials, while the existing NLO materials exhibit limitations such as low nonlinear absorption coefficients and/or small modulation depths, thereby severely impeding their practical application. Here we unveil that introducing Jahn-Teller distortion in a Mott-Hubbard system, (MA)CuX (MA=methylammonium; X=Cl, Br) affords the simultaneous attainment of a giant nonlinear absorption coefficient and substantial modulation depth. The optimized compound, (MA)CuCl, demonstrates a nonlinear absorption coefficient of (1.

An Unprecedented [BO]-Based Deep-Ultraviolet Transparent Nonlinear Optical Crystal by Superhalogen Substitution.

Solid-state structures with the superhalogen [BO] have thus far only been observed with a few compounds whose syntheses require high reaction temperatures and complicated procedures, while their optical properties remain almost completely unexplored. Herein, we report a facile, energy-efficient synthesis of the first [BO]-based deep-ultraviolet (deep-UV) transparent oxide K[BO(OH)](CO)(BO) ⋅ 7HO (KBCOB). Detailed structural characterization and analysis confirm that KBCOB possesses a rare four-in-one three-dimensional quasi-honeycomb framework, with three π-conjugated anions ([BO], [BO], and [CO]) and one non-π-conjugated anion ([BO]) in the one crystal.

Record Second-Harmonic Generation and Birefringence in an Ultraviolet Antimonate by Bond Engineering.

Oxides have attracted considerable attention owing to their potential for nonlinear optical (NLO) applications. Although significant progress has been achieved in optimizing the structural characteristics of primitives (corresponding to the simplest constituent groups, namely, cations/anions/neutral molecules) comprising the crystalline oxides, the role of the primitives' interaction in determining the resultant functional structure and optical properties has long been underappreciated and remains unclear. In this study, we employ a π-conjugated organic primitive confinement strategy to manipulate the interactions between primitives in antimonates and thereby significantly enhance the optical nonlinearity.

Giant Optical Anisotropy in a Covalent Molybdenum Tellurite via Oxyanion Polymerization.

Large birefringence is a crucial but hard-to-achieve optical parameter that is a necessity for birefringent crystals in practical applications involving modulation of the polarization of light in modern opto-electronic areas. Herein, an oxyanion polymerization strategy that involves the combination of two different types of second-order Jahn-Teller distorted units is employed to realize giant anisotropy in a covalent molybdenum tellurite. Mo(HO)TeO (MTO) exhibits a record birefringence value for an inorganic UV-transparent oxide crystalline material of 0.

Secondary-Bond-Driven Construction of a Polar Material Exhibiting Strong Broad-Spectrum Second-Harmonic Generation and Large Birefringence.

Considerable effort has been invested in the development of non-centrosymmetric (NCS) inorganic solids for ferroelectricity-, piezoelectricity- and, particularly, optical nonlinearity-related applications. While great progress has been made, a persistent problem is the difficulty in constructing NCS materials, which probably stems from non-directionality and unsaturation of the ionic bonds between metal counter-cations and covalent anionic modules. We report herein a secondary-bond-driven approach that circumvents the cancellation of dipole moments between adjacent anionic modules that has plagued second-harmonic generation (SHG) material design, and which thereby affords a polar structure with strong SHG properties.

Ultrashort Phase-Matching Wavelength and Strong Second-Harmonic Generation in Deep-UV-Transparent Oxyfluorides by Covalency Reduction.

The development of urgently-needed ultraviolet (UV)/deep-UV nonlinear optical (NLO) materials has been hindered by contradictory requirements of the microstructure, in particular the need for a strong second-harmonic generation (SHG) response as well as a short phase-matching (PM) wavelength. We herein employ a "de-covalency" band gap engineering strategy to adjust the optical linearity and nonlinearity. This has been achieved by assembling two types of transition-metal (TM) polyhedra ([TaO F ] and [TaF ]), affording the first tantalum-based deep-UV-transparent NLO materials, A Ta OF (A = K (KTOF), Rb (RTOF)).

Donor-π-Acceptor Porphyrin-Assisted Bifunctional Defect Passivation for Enhanced Temporal Domain-/Wavelength-Dependent Nonlinear Absorption Properties in Perovskite Films.

Perovskite layer defects are a primary inhibiting factor for their optical nonlinearity, which restricts their use in nonlinear photonics devices. Nevertheless, due to the variety of defect types, the passivation and repair of these defects remain challenging. Herein, a novel bifunctional passivation strategy was proposed, and the porphyrin with a donor-π-acceptor structure was designed to bifunctionally repair perovskite defects by linking different types of functional groups via acetylenic π-conjugated linkage bridges on both sides, thus improving the nonlinear optical (NLO) absorption properties of porphyrin-perovskite hybrid materials.

Giant Mid-Infrared Second-Harmonic Generation Response in a Densely-Stacked Van Der Waals Transition-Metal Oxychloride.

Second-harmonic generation (SHG) is a fundamental optical property of nonlinear optical (NLO) crystals. Thus far, it has proved difficult to engineer large SHG responses, particularly in the mid-infrared region, owing to the difficulty in simultaneously controlling the arrangement and density of functional NLO-active units. Herein, a new assembly strategy employing functional modules only, and aimed at maximizing the density and optimizing the spatial arrangement of highly efficient functional modules, has been applied to the preparation of NLO crystals, affording the van der Waals crystal MoO Cl .

Quadruple-Bidentate Nitrate-Ligated A Hg(NO ) (A=K, Rb): Strong Second-Harmonic Generation and Sufficient Birefringence.

The design of efficient nonlinear optical (NLO) crystals continues to pose significant challenges due to the difficulty of assembling polar NLO-active modules in an optimal additive fashion. We report herein the first NLO-active mercuric nitrates A Hg(NO ) (A=(KHNO), Rb (RHNO)), for which assembly is induced by ionic polarization of the d cations. The two new crystalline compounds are isostructural, featuring interesting pseudo-diamond-like structures with parallel [Hg(NO ) ] modules, and leading to strong powder second-harmonic generation (SHG) responses of 9.

Self-assembled stereomutation with supramolecular chirality inversion.

Supramolecular chirality is involved not only in biological events such as gene communication, replication, and enzyme catalysis but also in artificial self-assembly systems and aggregated materials. The precise control of supramolecular chirality, and especially supramolecular chirality inversion (SMCI), would deepen the understanding of chiral transfer and regulation in both living systems and artificial self-assembly systems, providing efficient ways to construct advanced chiral materials with an optimum assembly pathway necessary for various functions. In this review, the fundamental principles of SMCI are comprehensively summarized, with a focus on the helical assemblies having opposite handedness or chiroptical properties of the compositions.

Outstanding Quadratic to Septic Optical Nonlinearity at Dipolar Alkynylmetal-Porphyrin Hybrids.

Porphyrins are important macrocycles with applications in several areas including therapy, catalysis, and sensing. Strong nonlinear optical (NLO) responses are the key to fully exploiting the potential of these biocompatible molecules. We herein report that certain metal-alkynyl donor/nitro acceptor-functionalized porphyrins are attractive candidates for NLO applications.

Tuning anticancer properties and DNA-binding of Pt(ii) complexes alteration of nitrogen softness/basicity of tridentate ligands.

Nine tridentate Schiff base ligands of the type (N^N^O) were synthesized from reactions of primary amines {2-picolylamine (Py), -phenyl-1,2-diaminobenzene (PhN), and -phenyl-1,2-diaminoethane(EtN)} and salicylaldehyde derivatives {3-ethoxy (OEt), 4-diethylamine (NEt) and 4-hydroxy (OH)}. Complexes with the general formula Pt(N^N^O)Cl were synthesized by reacting KPtCl with the ligands in DMSO/ethanol mixtures. The ligands and their complexes were characterized by NMR spectroscopy, mass spectrometry and elemental analysis.

Defect-Dependent Nonlinear Absorption in the Lead-Free Double-Perovskite CsAgBiBr.

Lead-free perovskites have attracted increasing attention because they can address the toxicity and instability problems inherent to lead-halide perovskites. Furthermore, the nonlinear optical (NLO) properties of lead-free perovskites are rarely explored. Herein, we report significant NLO responses and defect-dependent NLO behavior of CsAgBiBr.

Toward Large Second-Harmonic Generation and Deep-UV Transparency in Strongly Electropositive Transition Metal Sulfates.

The development of deep-ultraviolet (DUV)/solar-blind UV nonlinear optical (NLO) crystals simultaneously possessing wide UV transparency, strong second-harmonic generation (SHG) response, and suitable birefringence is a major challenge in advanced laser technology. We herein propose a "cation compensation" strategy for strong optical nonlinearity in inorganic solids that is exemplified by the introduction of strongly electropositive transition metals (TMs). Following this strategy, the first d TM UV-transparent NLO sulfates, MF(SO) (M = Zr (ZFSO), Hf (HFSO)), have been synthesized.

Wide bandgaps and strong SHG responses of hetero-oxyfluorides by dual-fluorination-directed bandgap engineering.

A wide bandgap is an essential requirement for a nonlinear optical (NLO) material. However, it is very challenging to simultaneously engineer a wide bandgap and a strong second-harmonic generation (SHG) response, particularly in NLO materials containing second-order Jahn-Teller (SOJT) distorted units. Herein, we employ a bandgap engineering strategy that involves the dual fluorination of two different types of SOJT distorted units to realize remarkably wide bandgaps in the first examples of 5d-transition metal (TM) fluoroiodates.

Tuning the anticancer properties of Pt(ii) complexes structurally flexible -(2-picolyl)salicylimine ligands.

Three tridentate Schiff base ligands were synthesized from the reactions between 2-picolylamine and salicylaldehyde derivatives (3-ethoxy (OEt), 4-diethylamino (NEt) and 4-hydroxy (OH)). Complexes with the general formula Pt(N^N^O)Cl were obtained from reactions between the ligands and KPtCl. The ligands and their complexes were characterized by NMR spectroscopy, mass spectrometry and elemental analysis.

Isoreticular Design of KTiOPO-Like Deep-Ultraviolet Transparent Materials Exhibiting Strong Second-Harmonic Generation.

Second-harmonic generation (SHG) is of great technological importance for applications in nonlinear optics, but it remains challenging to engineer large SHG responses in the short-wavelength ultraviolet (UV) region owing to competing microstructure requirements. Herein, we report the first examples of d transition-metal-based (TM-based) deep-UV-transparent nonlinear optical (NLO) crystals MOFH (M = Zr (ZOF), Hf (HOF)), which exhibit unprecedented short UV absorption edges (below 190 nm). Evolving from the KTiOPO (KTP) structure by an isoreticular node substitution strategy, the three-dimensional frameworks of ZOF and HOF consist of corner-sharing [MOF] moieties that are new functional units in deep-UV NLO material design, conferring wide UV transparency and strong phase-matchable SHG response (2.

Additive-Triggered Polar Polymorph Formation: β-Sc(IO ) , a Promising Next-Generation Mid-Infrared Nonlinear Optical Material.

Noncentrosymmetric (NCS) solids have attracted interest for their potential in ferroelectric, piezoelectric, and nonlinear optical (NLO) devices, but their synthesis remains a major challenge. In this study, the additive Li CO triggers formation of an NCS precursor at an early nucleation stage, and plays a crucial role in the successful polymorphism transformation. The resultant metastable β-Sc(IO ) is a promising mid-infrared NLO crystal, with the strongest second-harmonic generation responses (2.

Giant Multi-Photon Absorption by Heptazine Organometalation.

Multi-photon absorption (MPA) is of increasing interest for applications in technologically important "windows" of the electromagnetic spectrum (near-infrared III, NIR-III, 1550-1870 nm; and the new 2080-2340 nm region); however, few molecules exist that display strong MPA at these long wavelengths. We herein report the syntheses of the first 2,5,8-s-heptazine-cored organometallic complexes, together with organic analogues. The complexes exhibit outstanding 3PA cross-sections in the NIR-III and exceptional 4PA cross-sections in the new 2080-2340 nm window.

Ultrawide Bandgap and Outstanding Second-Harmonic Generation Response by a Fluorine-Enrichment Strategy at a Transition-Metal Oxyfluoride Nonlinear Optical Material.

The development of nonlinear optical (NLO) materials has been hindered by competing microstructure requirements: the need to simultaneously engineer a large hyperpolarizability (a large second-harmonic generation (SHG)) and a wide HOMO-LUMO gap (a wide band gap). Herein, a non-centrosymmetric transition-metal (TM) oxyfluoride K (NbOF )(NbF ) (KNOF) with an extremely high F/O ratio is constructed in high yield. KNOF exhibits an extremely wide band gap (5.

Switching the Nonlinear Optical Absorption of Titanium Carbide MXene by Modulation of the Surface Terminations.

Surface terminations of two-dimensional materials should have a strong influence on the nonlinear optical (NLO) properties, but the relationship between surface terminations and NLO properties has not yet been reported. In this work, switching the NLO properties of MXenes (TiCT) via "surface terminations modulation" is explored. The surface terminations of TiCT are modulated by electrochemical treatment, resulting in different states (.

Outstanding Multi-Photon Absorption at π-Delocalizable Metallodendrimers.

Multi-photon absorption (MPA) has attracted interest for applications exploiting the tight spatial control of interaction volume and long wavelength excitation. However, a deficiency of molecules exhibiting higher-order nPA (n-photon absorption, n>2) and a lack of structure-property studies to define the key structural characteristics needed to optimize higher-order MPA performance have hindered practical development. We herein report the syntheses of second- and third-generation metallodendrimers and assessment of their nonlinear absorption, together with those of zero- and first-generation analogues.