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Electrically conductive coordination polymers (ECCPs), particularly those incorporating benzenehexathiol (BHT) ligands, are emerging as a distinctive class of electronic materials with tunable semiconducting and metallic properties. However, the exploration of novel ECCPs with low-symmetry structures and electrical anisotropy remains under development. Here, we report the on-water surface synthesis of a novel ECCP, namely Cu 5 BHT, which exhibits a low-symmetry structure and unique in-plane electrical anisotropy that differs from the well-known Cu 3 BHT phase. Utilizing imaging and diffraction techniques, we elucidate the unit cell and crystal structure of Cu 5 BHT, revealing an asymmetric arrangement of the kagome resembling lattice connected by two different secondary building units: square planar CuS 4 and non-planar Cu 2 S 4 . Theoretical studies indicate that Cu 5 BHT is metallic and exhibits in-plane electrical anisotropy due to the structure arranged in interconnected well-conducting CuS 4 chains and less-conducting Cu 2 S 4 slabs oriented along single crystal direction. Single-crystal electrical measurements confirm a metallic character characterized by the increase of conductance upon cooling. Notably, the measured conductance along different crystal directions within the ab plane unambiguously reveals a significant anisotropy, with an anisotropic factor reaching ~8. This work demonstrates a novel low-symmetry ECCP and highlights its potential for achieving in-plane electrical anisotropy., (© 2025 The Author(s). Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

The catalytic potential of flexible metal-organic frameworks (MOFs) remains underexplored, particularly in liquid-phase reactions. This study employs MIL-53(Cr), a prototypical "breathing" MOF capable of structural adaptation via pore size modulation, as a photocatalyst for the dehalogenation of aryl halides. Powder X-ray diffraction and Pair Distribution Function analyses reveal that organic solvents influence pore opening, while substrates and products dynamically adjust the framework configuration during catalysis. This structural flexibility enables precise tuning of photocatalytic efficiency via solvent-mediated control of the pore aperture. The results demonstrate that the dynamic behavior of MIL-53(Cr) facilitates enhanced catalytic activity and selectivity, advancing the application of flexible MOFs as tunable, enzyme-mimicking catalysts. These findings pave the way for the rational design of next-generation flexible photocatalysts., (© 2025 The Author(s). Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

The emerging laser writing represents an efficient and promising strategy for covalent two dimensional (2D)-patterning of graphene yet remains a challenging task due to the lack of applicable reagents. Here, we report a versatile approach for covalent laser patterning of graphene using a family of trivalent organic iodine compounds as effective reagents, allowing for the engraving of a library of functionalities onto the graphene surface. The relatively weak iodine-centered bonds within these compounds can readily undergo laser-induced cleavage to in situ generate radicals localized to the irradiated regions for graphene binding, thus completing the covalent 2D-structuring of this 2D-film. The tailor-made attachment of distinct functional moieties with varying electrical properties as well as their thermally reversible binding manner enables programming the surface properties of graphene. With this delicate strategy the bottleneck of a limited scope of functional groups patterned onto the graphene surface upon laser writing is tackled., (© 2024 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

Introducing continuous mesochannels into covalent organic frameworks (COFs) to increase the accessibility of their inner active sites has remained a major challenge. Here, we report the synthesis of COFs with an ordered bicontinuous mesostructure, via a block copolymer self-assembly-guided nanocasting strategy. Three different mesostructured COFs are synthesized, including two covalent triazine frameworks and one vinylene-linked COF. The new materials are endowed with a hierarchical meso/microporous architecture, in which the mesochannels exhibit an ordered shifted double diamond (SDD) topology. The hierarchically porous structure can enable efficient hole-electron separation and smooth mass transport to the deep internal of the COFs and consequently high accessibility of their active catalytic sites. Benefiting from this hierarchical structure, these COFs exhibit excellent performance in visible-light-driven catalytic NO removal with a high conversion percentage of up to 51.4 %, placing them one of the top reported NO-elimination photocatalysts. This study represents the first case of introducing a bicontinuous structure into COFs, which opens a new avenue for the synthesis of hierarchically porous COFs and for increasing the utilization degree of their internal active sites., (© 2024 Wiley‐VCH GmbH.)

Electron-phonon interactions, crucial in condensed matter, are rarely seen in Metal-Organic Frameworks (MOFs). Detecting these interactions typically involves analyzing luminescence in lanthanide- or actinide-based compounds. Prior studies on Ln- and Ac-based MOFs at high temperatures revealed additional peaks, but these were too faint for thorough analysis. In our research, we fabricated a high-quality, crystalline uranium-based MOF (KIT-U-1) thin film using a layer-by-layer method. Under UV light, this film showed two distinct "hot bands," indicating a strong electron-phonon interaction. At 77 K, these bands were absent, but at 300 K, a new emission band appeared with half the intensity of the main luminescence. Surprisingly, a second hot band emerged above 320 K, deviating from previous findings in rare-earth compounds. We conducted a detailed ab-initio analysis employing time-dependent density functional theory to understand this unusual behaviour and to identify the lattice vibration responsible for the strong electron-phonon coupling. The KIT-U-1 film's hot-band emission was then utilized to create a highly sensitive, single-compound optical thermometer. This underscores the potential of high-quality MOF thin films in exploiting the unique luminescence of lanthanides and actinides for advanced applications., (© 2023 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

Linear conjugated polymers have attracted significant attention in organic electronics in recent decades. However, despite intrachain π-delocalization, interchain hopping is their transport bottleneck. In contrast, two-dimensional (2D) conjugated polymers, as represented by 2D π-conjugated covalent organic frameworks (2D c-COFs), can provide multiple conjugated strands to enhance the delocalization of charge carriers in space. Herein, we demonstrate the first example of thiophene-based 2D poly(arylene vinylene)s (PAVs, 2DPAV-BDT-BT and 2DPAV-BDT-BP, BDT=benzodithiophene, BT=bithiophene, BP=biphenyl) via Knoevenagel polycondensation. Compared with 2DPAV-BDT-BP, the fully thiophene-based 2DPAV-BDT-BT exhibits enhanced planarity and π-delocalization with a small band gap (1.62 eV) and large electronic band dispersion, as revealed by the optical absorption and density functional calculations. Remarkably, temperature-dependent terahertz spectroscopy discloses a unique band-like transport and outstanding room-temperature charge mobility for 2DPAV-BDT-BT (65 cm 2  V -1  s -1 ), which far exceeds that of the linear PAVs, 2DPAV-BDT-BP, and the reported 2D c-COFs in the powder form. This work highlights the great potential of thiophene-based 2D PAVs as candidates for high-performance opto-electronics., (© 2023 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

Flexible porous frameworks are at the forefront of materials research. A unique feature is their ability to open and close their pores in an adaptive manner induced by chemical and physical stimuli. Such enzyme-like selective recognition offers a wide range of functions ranging from gas storage and separation to sensing, actuation, mechanical energy storage and catalysis. However, the factors affecting switchability are poorly understood. In particular, the role of building blocks, as well as secondary factors (crystal size, defects, cooperativity) and the role of host-guest interactions, profit from systematic investigations of an idealized model by advanced analytical techniques and simulations. The review describes an integrated approach targeting the deliberate design of pillared layer metal-organic frameworks as idealized model materials for the analysis of critical factors affecting framework dynamics and summarizes the resulting progress in their understanding and application., (© 2023 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

Two-dimensional conjugated metal-organic frameworks (2D c-MOFs) are emerging as a unique class of electronic materials. However, 2D c-MOFs with band gaps in the Vis-NIR and high charge carrier mobility are rare. Most of the reported conducting 2D c-MOFs are metallic (i.e. gapless), which largely limits their use in logic devices. Herein, we design a phenanthrotriphenylene-based, D 2h -symmetric π-extended ligand (OHPTP), and synthesize the first rhombic 2D c-MOF single crystals (Cu 2 (OHPTP)). The continuous rotation electron diffraction (cRED) analysis unveils the orthorhombic crystal structure at the atomic level with a unique slipped AA stacking. The Cu 2 (OHPTP) is a p-type semiconductor with an indirect band gap of ≈0.50 eV and exhibits high electrical conductivity of 0.10 S cm -1 and high charge carrier mobility of ≈10.0 cm 2  V -1  s -1 . Theoretical calculations underline the predominant role of the out-of-plane charge transport in this semiquinone-based 2D c-MOF., (© 2023 Wiley-VCH GmbH.)

Flavoprotein monooxygenases are a versatile group of enzymes for biocatalytic transformations. Among these, group E monooxygenases (GEMs) catalyze enantioselective epoxidation and sulfoxidation reactions. Here, we describe the crystal structure of an indole monooxygenase from the bacterium Variovorax paradoxus EPS, a GEM designated as VpIndA1. Complex structures with substrates reveal productive binding modes that, in conjunction with force-field calculations and rapid mixing kinetics, reveal the structural basis of substrate and stereoselectivity. Structure-based redesign of the substrate cavity yielded variants with new substrate selectivity (for sulfoxidation of benzyl phenyl sulfide) or with greatly enhanced stereoselectivity (from 35.1 % to 99.8 % ee for production of (1S,2R)-indene oxide). This first determination of the substrate binding mode of GEMs combined with structure-function relationships opens the door for structure-based design of these powerful biocatalysts., (© 2023 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

Vinylene-linked two-dimensional covalent organic frameworks (V-2D-COFs) have shown great promise in electronics and optoelectronics. However, only a few reactions for V-2D-COFs have been developed hitherto. Besides the kinetically low reversibility of C=C bond formation, another underlying issue facing the synthesis of V-2D-COFs is the attainment of high (E)-alkene selectivity to ensure the appropriate symmetry of 2D frameworks. Here, we tailor the E/Z selectivity of the Wittig reaction by employing a proper catalyst (i.e., Cs 2 CO 3 ) to obtain more stable intermediates and elevating the temperature across the reaction barrier. Subsequently, the Wittig reaction is innovatively utilized for the synthesis of four crystalline V-2D-COFs by combining aldehydes and ylides. Importantly, the efficient conjugation and decent crystallinity of the resultant V-2D-COFs are demonstrated by their high charge carrier mobilities over 10 cm 2  V -1  s -1 , as revealed by non-contact terahertz (THz) spectroscopy., (© 2022 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

Single-atom catalysts (SACs), as promising alternatives to Pt-based catalysts, suffer from the limited choice of center metals and low single-atom loading. Here, we report a pentacoordinated Zr-based SAC with nontrivial axial O ligands (denoted O-Zr-N-C) for oxygen reduction reaction (ORR). The O ligand downshifts the d-band center of Zr and confers Zr sites with stable local structure and proper adsorption capability for intermediates. Consequently, the ORR performance of O-Zr-N-C prominently surpasses that of commercial Pt/C, achieving a half-wave potential of 0.91 V vs. reversible hydrogen electrode and outstanding durability (92 % current retention after 130-hour operation). Moreover, the Zr site shows good resistance towards aggregation, enabling the synthesis of Zr-based SAC with high loading (9.1 wt%). With the high-loading catalyst, the zinc-air battery (ZAB) delivers a record-high power density of 324 mW cm -2 among those of SAC-based ZABs., (© 2022 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

Exotic oxidation states of the first-row transition metals have recently attracted much interest. In order to investigate the oxidation states of a series of iron-oxalate complexes, an aqueous solution of iron(III) nitrate and oxalic acid was studied by infrared free liquid matrix-assisted laser desorption/ionization as well as ionspray mass spectrometry. Here, we show that iron is not only detected in its common oxidation states +II and +III, but also in its unusual oxidation state +I, detectable in both positive-ion and in negative-ion modes, respectively. Vibrational spectra of the gas phase anionic iron oxalate complexes [Fe III (C 2 O 4 ) 2 ] - , [Fe II (C 2 O 4 )CO 2 ] - , and [Fe I (C 2 O 4 )] - were measured by means of infrared photodissociation spectroscopy and their structures were assigned by comparison to anharmonic vibrational spectra based on second-order perturbation theory., (© 2022 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

2D conjugated metal-organic frameworks (2D c-MOFs) are emerging as electroactive materials for chemiresistive sensors, but selective sensing with fast response/recovery is a challenge. Phthalocyanine-based Ni 2 [MPc(NH) 8 ] 2D c-MOF films are presented as active layers for polarity-selective chemiresisitors toward water and volatile organic compounds (VOCs). Surface-hydrophobic modification by grafting aliphatic alkyl chains on 2D c-MOF films decreases diffused analytes into the MOF backbone, resulting in a considerably accelerated recovery progress (from ca. 50 to ca. 10 s) during humidity sensing. Toward VOCs, the sensors deliver a polarity-selective response among alcohols but no signal for low-polarity aprotic hydrocarbons. The octadecyltrimethoxysilane-modified Ni 2 [MPc(NH) 8 ] based sensor displays high-performance methanol sensing with fast response (36 s)/recovery (13 s) and a detection limit as low as 10 ppm, surpassing reported room-temperature chemiresistors., (© 2021 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

Two-dimensional polymers (2DPs) are a class of atomically/molecularly thin crystalline organic 2D materials. They are intriguing candidates for the development of unprecedented organic-inorganic 2D van der Waals heterostructures (vdWHs) with exotic physicochemical properties. In this work, we demonstrate the on-water surface synthesis of large-area (cm 2 ), monolayer 2D polyimide (2DPI) with 3.1-nm lattice. Such 2DPI comprises metal-free porphyrin and perylene units linked by imide bonds. We further achieve a scalable synthesis of 2DPI-graphene (2DPI-G) vdWHs via a face-to-face co-assembly of graphene and 2DPI on the water surface. Remarkably, femtosecond transient absorption spectroscopy reveals an ultra-fast interlayer charge transfer (ca. 60 fs) in the resultant 2DPI-G vdWH upon protonation by acid, which is equivalent to that of the fastest reports among inorganic 2D vdWHs. Such large interlayer electronic coupling is ascribed to the interlayer cation-π interaction between 2DP and graphene., (© 2021 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

Noble-metal chalcogenides, dichalcogenides, and phosphochalcogenides are an emerging class of two-dimensional materials. Quantum confinement (number of layers) and defect engineering enables their properties to be tuned over a broad range, including metal-to-semiconductor transitions, magnetic ordering, and topological surface states. They possess various polytypes, often of similar formation energy, which can be accessed by selective synthesis approaches. They excel in mechanical, optical, and chemical sensing applications, and feature long-term air and moisture stability. In this Minireview, we summarize the recent progress in the field of noble-metal chalcogenides and phosphochalcogenides and highlight the structural complexity and its impact on applications., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Despite the recent progress in the synthesis of crystalline boronate ester covalent organic frameworks (BECOFs) in powder and thin-film through solvothermal method and on-solid-surface synthesis, respectively, their applications in electronics, remain less explored due to the challenges in thin-film processability and device integration associated with the control of film thickness, layer orientation, stability and crystallinity. Moreover, although the crystalline domain sizes of the powder samples can reach micrometer scale (up to ≈1.5 μm), the reported thin-film samples have so far rather small crystalline domains up to 100 nm. Here we demonstrate a general and efficient synthesis of crystalline two-dimensional (2D) BECOF films composed of porphyrin macrocycles and phenyl or naphthyl linkers (named as 2D BECOF-PP or 2D BECOF-PN) by employing a surfactant-monolayer-assisted interfacial synthesis (SMAIS) on the water surface. The achieved 2D BECOF-PP is featured as free-standing thin film with large single-crystalline domains up to ≈60 μm 2 and tunable thickness from 6 to 16 nm. A hybrid memory device composed of 2D BECOF-PP film on silicon nanowire-based field-effect transistor is demonstrated as a bio-inspired system to mimic neuronal synapses, displaying a learning-erasing-forgetting memory process., (© 2020 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.)

Single-layer and multi-layer 2D polyimine films have been achieved through interfacial synthesis methods. However, it remains a great challenge to achieve the maximum degree of crystallinity in the 2D polyimines, which largely limits the long-range transport properties. Here we employ a surfactant-monolayer-assisted interfacial synthesis (SMAIS) method for the successful preparation of porphyrin and triazine containing polyimine-based 2D polymer (PI-2DP) films with square and hexagonal lattices, respectively. The synthetic PI-2DP films are featured with polycrystalline multilayers with tunable thickness from 6 to 200 nm and large crystalline domains (100-150 nm in size). Intrigued by high crystallinity and the presence of electroactive porphyrin moieties, the optoelectronic properties of PI-2DP are investigated by time-resolved terahertz spectroscopy. Typically, the porphyrin-based PI-2DP 1 film exhibits a p-type semiconductor behavior with a band gap of 1.38 eV and hole mobility as high as 0.01 cm 2  V -1  s -1 , superior to the previously reported polyimine based materials., (© 2020 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.)

Covalent organic frameworks (COFs) allow elaborate manufacture of ordered one-dimensional channels in the crystal. We defined a superlattice of COFs by engineering channels with a persistent triangular shape and discrete pore size. We observed a size-recognition regime that is different from the characteristic adsorption of COFs, whereby pore windows and walls were cooperative so that triangular apertures sorted molecules of one-atom difference and notch nanogrooves confined them into single-file molecular chains. The recognition and confinement were accurately described by sensitive spectroscopy and femtosecond dynamic simulations. The resulting COFs enabled instantaneous separation of mixtures at ambient temperature and pressure. This study offers an approach to merge precise recognition, selective transport, and instant separation in synthetic 1D channels., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A two-dimensional (2D) sp 2 -carbon-linked conjugated polymer framework (2D CCP-HATN) has a nitrogen-doped skeleton, a periodical dual-pore structure and high chemical stability. The polymer backbone consists of hexaazatrinaphthalene (HATN) and cyanovinylene units linked entirely by carbon-carbon double bonds. Profiting from the shape-persistent framework of 2D CCP-HATN integrated with the electrochemical redox-active HATN and the robust sp 2 carbon-carbon linkage, 2D CCP-HATN hybridized with carbon nanotubes shows a high capacity of 116 mA h g -1 , with high utilization of its redox-active sites and superb cycling stability (91 % after 1000 cycles) and rate capability (82 %, 1.0 A g -1 vs. 0.1 A g -1 ) as an organic cathode material for lithium-ion batteries., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A rapid and scalable synthesis of six new imine-linked highly porous and crystalline COFs is presented that feature exceptionally high chemical stability in harsh environments including conc. H 2 SO 4 (18 m), conc. HCl (12 m), and NaOH (9 m). This is because of the presence of strong interlayer C-H⋅⋅⋅N hydrogen bonding among the individual layers, which provides significant steric hindrance and a hydrophobic environment around the imine (-C=N-) bonds, thus preventing their hydrolysis in such an abrasive environment. These COFs were further converted into porous, crystalline, self-standing, and crack-free COF membranes (COFMs) with extremely high chemical stability for their potential applications for sulfuric acid recovery. The as-synthesized COFMs exhibit unprecedented permeance for acetonitrile (280 Lm -2  h -1  bar -1 ) and acetone (260 Lm -2  h -1  bar -1 )., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

In all known Group 5 transition-metal dichalcogenide monolayers (MLs), the metal centers carry a spin, and their ground-state phases are either metallic or semiconducting with indirect band gaps. Here, on grounds of first-principles calculations, we report that the Haeckelite polytypes 1S-NbX 2 (X=S, Se, Te) are diamagnetic direct-band-gap semiconductors even though the Nb atoms are in the 4+ oxidation state. In contrast, 1S-VX 2 MLs are antiferromagnetically coupled indirect-band-gap semiconductors. The 1S phases are thermodynamically and dynamically stable but of slightly higher energy than their 1H and 1T ML counterparts. 1S-NbX 2 MLs are excellent candidates for optoelectronic applications owing to their small band gaps (between 0.5 and 1 eV). Moreover, 1S-NbS 2 shows a particularly high hole mobility of 2.68×10 3  cm 2  V -1  s -1 , which is significantly higher than that of MoS 2 and comparable to that of WSe 2 ., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Covalent organic frameworks (COFs) have emerged as a tailor-made platform for designing layered two-dimensional polymers. However, most of them are obtained as neutral porous materials. Here, we report the construction of ionic crystalline porous COFs with positively charged walls that enable the creation of well aligned yet spatially confined ionic interface. The unconventional reversed AA-stacking mode alternately orientates the cationic centers to both sides of the walls; the ionic interface endows COFs with unusual electrostatic functions. Because all of the walls are decorated with electric dipoles, the uptake of CO 2 is enhanced by three fold compared to the neutral analog. By virtue of sufficient open space between cations, the ionic interface exhibits exceptional accessibility, efficiency, and selectivity in ion exchange to trap anionic pollutants. These findings suggest that construction of the ionic interface of COFs offers a new way to structural and functional designs., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

We use cryogenic ion vibrational spectroscopy to characterize the structure and fluxionality of the magic number boron cluster B 13 + . The infrared photodissociation (IRPD) spectrum of the D 2 -tagged all- 11 B isotopologue of B 13 + is reported in the spectral range from 435 to 1790 cm -1 and unambiguously assigned to a planar boron double wheel structure based on a comparison to simulated IR spectra of low energy isomers from density-functional-theory (DFT) computations. Born-Oppenheimer DFT molecular dynamics simulations show that B 13 + exhibits internal quasi-rotation already at 100 K. Vibrational spectra derived from these simulations allow extracting the first spectroscopic evidence from the IRPD spectrum for the exceptional fluxionality of B 13 + ., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

We have studied the magnetic properties of the SURMOF-2 series of metal-organic frameworks (MOFs). Contrary to bulk MOF-2 crystals, where Cu(2+) ions form paddlewheels and are antiferromagnetically coupled, in this case the Cu(2+) ions are connected via carboxylate groups in a zipper-like fashion. This unusual coupling of the spin 1/2 ions within the resulting one-dimensional chains is found to stabilize a low-temperature, ferromagnetic (FM) phase. In contrast to other ordered 1D systems, no strong magnetic fields are needed to induce the ferromagnetism. The magnetic coupling constants describing the interaction between the individual metal ions have been determined in SQUID experiments. They are fully consistent with the results of ab initio DFT electronic structure calculations. The theoretical results allow the unusual magnetic behavior of this exotic, yet easy-to-fabricate, material to be described in a detailed fashion., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Two new chemically stable triazine- and phenyl-core-based crystalline porous polymers (CPPs) have been synthesized using a single-step template-free solvothermal route. Unique morphological diversities were observed for these CPPs [2,3-DhaTta (ribbon) and 2,3-DhaTab (hollow sphere)] by simply altering the linker planarity. A detailed time-dependent study established a significant correlation between the molecular level structures of building blocks with the morphology of CPPs. Moreover, a DFT study was done for calculating the interlayer stacking energy, which revealed that the extent of stacking efficiency is responsible for governing the morphological diversity in these CPPs., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

For inorganic semiconductors crystalline order leads to a band structure which gives rise to drastic differences to the disordered material. An example is the presence of an indirect band gap. For organic semiconductors such effects are typically not considered, since the bands are normally flat, and the band-gap therefore is direct. Herein we show results from electronic structure calculations demonstrating that ordered arrays of porphyrins reveal a small dispersion of occupied and unoccupied bands leading to the formation of a small indirect band gap. We demonstrate herein that such ordered structures can be fabricated by liquid-phase epitaxy and that the corresponding crystalline organic semiconductors exhibit superior photophysical properties, including large charge-carrier mobility and an unusually large charge-carrier generation efficiency. We have fabricated a prototype organic photovoltaic device based on this novel material exhibiting a remarkable efficiency., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Transition-metal chalcogenide (TMC) nanoflakes of composition MX2 (where M=Ti, Zr and Hf; X=S and Se) crystallize preferentially in equilateral hexagons and exhibit a pronounced lateral quantum confinement. The hexagonal shape of octahedral (1T) TMC nanoflakes is the result of charge localization at the edges/vertices and the resulting Coulomb repulsion. Independent of their size, all nanoflakes have the Mn X2n-2 stoichiometry and thus an unoxidized metal center which results in dopant states. These states become relevant for small nanoflakes and lead to metallic character, but for larger nanoflakes (>6 nm) the 2D monolayer properties dominate. Finally, coordination of Lewis bases at the nanoflake edges has no significant effect on the electronic structure of these species confirming the viability of colloidal synthetic approaches., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The structure and electronic structure of layered noble-transition-metal dichalcogenides MX2 (M=Pt and Pd, and chalcogenides X=S, Se, and Te) have been investigated by periodic density functional theory (DFT) calculations. The MS2 monolayers are indirect band-gap semiconductors whereas the MSe2 and MTe2 analogues show significantly smaller band gap and can even become semimetallic or metallic materials. Under mechanical strain these MX2 materials become quasi-direct band-gap semiconductors. The mechanical-deformation and electron-transport properties of these materials indicate their potential application in flexible nanoelectronics., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A strong bond: A strategy based on intramolecular hydrogen-binding interactions in 2D covalent organic frameworks (COFs) is shown to improve the crystallinity, porosity, and chemical stability of the material. The concept is validated by removing the hydrogen-bonding interaction in the methoxy analog which showed a lower stability and crystallinity., (Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)