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Here we present a colloidal approach to synthesize bismuth chalcohalide nanocrystals (BiEX NCs, in which E=S, Se and X=Cl, Br, I). Our method yields orthorhombic elongated BiEX NCs, with BiSCl crystallizing in a previously unknown polymorph. The BiEX NCs display a composition‐dependent band gap spanning the visible spectral range and absorption coefficients exceeding 105 cm−1. The BiEX NCs show chemical stability at standard laboratory conditions and form colloidal inks in different solvents. These features enable the solution processing of the NCs into robust solid films yielding stable photoelectrochemical current densities under solar‐simulated irradiation. Overall, our versatile synthetic protocol may prove valuable in accessing colloidal metal chalcohalide nanomaterials at large and contributes to establish metal chalcohalides as a promising complement to metal chalcogenides and halides for applied nanotechnology. [ABSTRACT FROM AUTHOR]

Anthracene derivative compounds are currently investigated because of their unique physical properties (e.g. bright luminescence and emission tunability), which make them ideal candidates for advanced optoelectronic devices. Intermolecular interactions are the basis of the tunability of the optical and electronic properties of these compounds, whose prediction and exploitation benefit from knowledge of the crystal structure and the packing architecture. Polymorphism can occur due to the weak intermolecular interactions, requiring detailed structural analysis to clarify the origin of observed material property modifications. Here, two silylethyne‐substituted anthracene compounds are characterized by single‐crystal synchrotron X‐ray diffraction, identifying a new polymorph in the process. Additionally, laser confocal microscopy and fluorescence lifetime imaging microscopy confirm the results obtained by the X‐ray diffraction characterization, i.e. shifting the substituents towards the external benzene rings of the anthracene unit favours π–π interactions, impacting on both the morphology and the microscopic optical properties of the crystals. The compounds with more isolated anthracene units feature shorter lifetime and emission spectra, more similar to those of isolated molecules. The crystallographic study, supported by the optical investigation, sheds light on the influence of non‐covalent interactions on the crystal packing and luminescence properties of anthracene derivatives, providing a further step towards their efficient use as building blocks in active components of light sources and photonic networks. [ABSTRACT FROM AUTHOR]

The Open Chemistry Database (OChemDb) is a new free online portal which uses an appropriately designed database of already solved crystal structures. It makes freely available computational and graphical tools for searching and analysing crystal‐chemical information of organic, metal–organic and inorganic structures, and providing statistics on desired bond distances, bond angles, torsion angles and space groups. Atom types have been classified by an identifier code containing information about the chemical topology and local environment. The crystallographic data used by OChemDb are acquired from the CIFs contained in the free small‐molecule Crystallography Open Database (COD). OChemDb offers easy‐to‐use and intuitive options for searching. It is updated by following the continuous growth of information stored in the COD. It can be of great utility for structural chemistry, in particular in the process of determination of a new crystal structure, and for any discipline involving crystalline structure knowledge. The use of OChemDb requires only a web browser and an internet connection. Every device (mobile or desktop) and every operating system is able to use OChemDb by accessing its web page. Examples of application of OChemDb are reported. [ABSTRACT FROM AUTHOR]

The hybrid big bang–big crunch algorithm is a combination of a global optimization algorithm inspired by one of the theories of the evolution of the universe, named the big bang and big crunch theory, and the simulated annealing method. The procedure was implemented in the latest version of the program EXPO and applied to crystal‐structure solution from powder diffraction data. Several aspects of the hybrid big bang–big crunch algorithm can be further optimized with the aim of obtaining good quality solutions in a shorter computation time. In the present study, the hybrid big bang–big crunch procedure has been combined with the greedy randomized adaptive search procedure (GRASP) and some steps of the algorithm have been improved. The new approach, implemented in the EXPO package, has been successfully tested on numerous known crystal structures. [ABSTRACT FROM AUTHOR]

The Shift_and_Fix procedure is a new method which has been developed for improving the quality of a structure model obtained by the ab initio solution process from powder diffraction data. The main features of the new approach, which is fully automatic, are as follows: ( a) the structure model usually attained at the end of the phasing process by direct methods is shifted partly and randomly; ( b) a combination of Fourier map calculation and least-squares cycles has been designed for relocating the shifted atoms onto positions which can finally be moved onto the true ones by the standard model optimization approaches; ( c) the Fourier map is calculated using coefficients which depend on the chemical content of the compound under study. When the figure of merit for selecting the best set of phases derived by direct methods does not work well, the ALLTRIALS strategy can be applied: it aims to investigate, automatically and sequentially, all the stored direct methods phasing sets and pick up the correct solution. The Shift_and_Fix method has been applied for improving the structure model calculated by each one of the phasing sets processed by ALLTRIALS. It has been implemented in the computer program EXPO and proved to be effective in providing a better ALLTRIALS outcome and increasing the probability of succeeding in the ab initio powder solution. [ABSTRACT FROM AUTHOR]

Innovative methodologies, introduced in the software EXPO and working both in the reciprocal and in the direct space, can be successfully adopted for solving crystal structure by X-ray powder diffraction data. The principles underlying these methodologies are summarized. Three representative examples of crystal structure solution of the peptides Z-(Aib)2-OH, Z-(Aib)3-O- t-Bu and Z-(Aib)4-OH are discussed in relation to their different degree of structure complexity. [ABSTRACT FROM AUTHOR]

Three new proton transfer compounds, [2-ammonio-5-methylcarboxybenzene perchlorate (1), (C8H10NO2+·ClO4−), 4-(ammoniomethyl)carboxybenzene nitrate (2), (C8H10NO2+·NO3−), and 4-(ammoniomethyl)carboxybenzene perchlorate (3), (C8H10NO2+·ClO4−)], have been synthesized, their IR modes of vibrations have been assigned and their crystal structures studied by means of single-crystal X-ray diffraction. Their asymmetric units consist of one cation and one anion for both compounds (1) and (2). However, the crystal structure of compound (3) is based on a pair of cations and a pair of anions in its asymmetric unit. The three-dimensional Hirshfeld surface analysis and the two-dimensional fingerprint maps revealed that the three structures are dominated by H...O/O...H and H...H contacts. The strongest hydrogen-bonding interactions are associated with O-H...O and N-H...O constituting the highest fraction of approximately 50%, followed by those of the H...H type contributing 20%. Other close contacts are also present, including weak C...H/H...C contacts (with about 10%). [ABSTRACT FROM AUTHOR]

QUALX2.0 is the new version of QUALX, a computer program for qualitative phase analysis by powder diffraction data. The previous version of QUALX was able to carry out phase identification by querying the PDF-2 commercial database. The main novelty of QUALX2.0 is the possibility of querying also a freely available database, POW_COD. POW_COD has been built up by starting from the structure information contained in the Crystallography Open Database (COD). The latter is a growing collection of diffraction data, freely downloadable from the web, corresponding to inorganic, metal-organic, organic and mineral structures. QUALX2.0 retains the main capabilities of the previous version: ( a) automatically estimating and subtracting the background; ( b) locating the experimental diffraction peaks; ( c) searching the database for single-phase pattern(s) best matching to the experimental powder diffraction data; ( d) taking into account suitable restraints in the search; ( e) performing a semi-quantitative analysis; ( f) enabling the change of default choices and strategies via a user-friendly graphic interface. The advances of QUALX2.0 with respect to QUALX include (i) a wider variety of types of importable ASCII file containing the experimental diffraction pattern and (ii) new search-match options. The program, written in Fortran and C++, runs on PCs under the Windows operating system. The POW_COD database is exported in SQLite3 format. [ABSTRACT FROM AUTHOR]

EXPO2013, the heir of EXPO2009, has been enriched by a variety of new algorithms and graphical tools aiming at strengthening the individual steps of the powder structure solution pathway. Particular attention has been addressed to the procedures devoted to improving structural models provided by direct methods in ab initio approaches. In addition, a new procedure has been implemented, working in direct space, which may be chosen by the user as an alternative to the traditional simulated annealing algorithm. [ABSTRACT FROM AUTHOR]

The big bang-big crunch method is a global optimization approach developed upon the analogy of one of the cosmological theories of the evolution of the universe. It has been suitably combined with a simulated annealing algorithm and used for solving crystal structure from powder diffraction data in direct space. When compared with the traditional simulated annealing method, it provides a significant advance: good solutions are attained in a shorter time. The new method has been implemented in the EXPO package. Its successful application is demonstrated with examples of already known structures. [ABSTRACT FROM AUTHOR]

The new method RAMM (random-model-based method) has been developed and implemented in the EXPO computing program for improving the ab initio crystal structure solution process. When the available information consists of only the experimental powder diffraction pattern and the chemical formula of the compound under study, the classical structure solution approach follows two main steps: (1) phasing by direct methods (or by Patterson methods) in order to obtain a structure model (this last is usually incomplete and/or approximate); (2) improving the model by structure optimization techniques. This article proposes the alternative procedure RAMM, which skips step (1) and supplies a fully random model to step (2). This model is then submitted to effective structure optimization tools present in EXPO- wLSQ (weighted least squares), RBM (resolution bias minimization) and COVMAP (a procedure of electron density modification based on the concept of covariance between points of the map) - which are able to lead to the correct structure. RAMM is based on a cyclic process, generating several random models which are then optimized. The process stops automatically when it recognizes the correct structure. [ABSTRACT FROM AUTHOR]

A new procedure (COVMAP) has been developed with the aim of recovering the full structure from very poor models, such as those provided by direct methods in unfavorable conditions. The procedure is based on the concept of covariance between points of an electron density map, mathematically set out by the authors in a recent paper: i.e. the density at one point depends on the density at another point of the map if their covariance is not vanishing. This concept suggested a procedure of electron density modification that uses pairs of model peaks to restrict the region where the density modification should be applied. Such modified densities lead to additional peaks, which in turn are submitted to two other important phasing tools present in EXPO2011, the resolution bias minimization and weighted least-squares procedures, which relocate, refine or reject these peaks. The procedure is cyclic and often leads to the correct structure even if the starting model is very poor. [ABSTRACT FROM AUTHOR]

Quite recently two papers have been published [Giacovazzo & Mazzone (2011). Acta Cryst. A 67, 210-218; Giacovazzo et al. (2011). Acta Cryst. A 67, 368-382] which calculate the variance in any point of an electron-density map at any stage of the phasing process. The main aim of the papers was to associate a standard deviation to each pixel of the map, in order to obtain a better estimate of the map reliability. This paper deals with the covariance estimate between points of an electron-density map in any space group, centrosymmetric or non-centrosymmetric, no matter the correlation between the model and target structures. The aim is as follows: to verify if the electron density in one point of the map is amplified or depressed as an effect of the electron density in one or more other points of the map. High values of the covariances are usually connected with undesired features of the map. The phases are the primitive random variables of our probabilistic model; the covariance changes with the quality of the model and therefore with the quality of the phases. The conclusive formulas show that the covariance is also influenced by the Patterson map. Uncertainty on measurements may influence the covariance, particularly in the final stages of the structure refinement; a general formula is obtained taking into account both phase and measurement uncertainty, valid at any stage of the crystal structure solution. [ABSTRACT FROM AUTHOR]

The article describes an atom-matching-based figure of merit (AMB FOM) which was developed and implemented in the EXPO2009 systematic decomposition program in order to enhance the efficiency of the crystal phasing process. The disadvantages and limited ability of the standard FOM are explored. According to the authors, one of the advantages of using the AMB FOM is its ability to regroup trial solutions in batches, which collect trials with models sharing a high percentage of atoms.

Powder pattern indexing can still be a challenge, despite the great recent advances in theoretical approaches, computer speed and experimental devices. More plausible unit cells, belonging to different crystal systems, are frequently found by the indexing programs, and recognition of the correct one may not be trivial. The task is, however, of extreme importance: in case of failure a lot of effort and computing time may be wasted. The classical figures of merit for estimating the unit-cell reliability {i.e. M20 [de Wolff (1968). J. Appl. Crys 108-113] and FN [Smith & Snyder (1979). J. Appl. Cryst. 12, 60-65]} sometimes fail. For this reason, a new figure of merit has been introduced in N-TREOR09, the updated version of the indexing package N-TREOR [Altomare, Giacovazzo, Guagliardi, Moliterni, Rizzi & Werner (2000). J. Appl. Cryst. 33, ]180-]186 combining the information supplied by M20 with additional parameters such as the number of unindexed lines, the degree of overlap in the pattern (the so- called number of statistically independent observations), the symmetry deriving from the automatic evaluation of the extinction group, and the agreement between the calculated and observed profiles. The use of the new parameters requires a dramatic modification of the procedures used worldwide: in the approach presented here, extinction symbol and unit-cell determination are simultaneously estimated. N-TREOR09 benefits also from an improved indexing procedure in the triclinic system and has been integrated into EXP02009, the updated version of EXP02004 [Altomare, Caliandro, Camalli, Cuocci, Giacovazzo, Moliterni & Rizzi (2004). J. Appl. Cryst. 37, 1025-]028] The application of the new procedure to a large set of test structures is described. [ABSTRACT FROM AUTHOR]

The article discusses the application of the joint probability distribution function method to multiple-wavelength anomalous dispersion (MAD) powder data. It points out the formulas resulting from the distribution calculations that enabled the solution to the crystal structures. It suggests that the mathematical approach of the MAD powder data has provided two types of formulas in estimating the phases of crystal structure provided that the anomalous substructure is known.

Fourier syntheses are always affected by series-termination errors, which generate sets of positive and negative ripples around each main peak in the map. The interaction among the ripples distorts the profile of the map and moves peaks away from their correct positions. In a previous paper [Altomare et al. (2008). Acta Cryst. A64, 326-336] an algorithm was described which reduces the resolution bias by removing the effects of the ripples in direct space. In this paper the correction is performed in reciprocal space: the effect of the ripples on the atomic scattering factors is calculated and subtracted from the usual atomic scattering factors. The modified scattering factors are used to calculate new structure factors, from which more accurate electron-density maps may be obtained. The experimental tests show that the procedure minimizes the effects of the resolution bias and provides atomic positions that are more accurate than those provided by traditional approaches. [ABSTRACT FROM AUTHOR]

A new joint probability distribution function method is described to find the anomalous scatterer substructure from powder data. The method requires two wavelengths; the conclusive formulas provide estimates of the substructure structure factor moduli, from which the anomalous scatterer positions can be found by Patterson or direct methods. The theory has been preliminarily applied to two compounds, the first having Pt and the second having Fe as anomalous scatterer. Both substructures were correctly identified. [ABSTRACT FROM AUTHOR]

Fourier syntheses providing electron density maps are usually affected by truncation effects due to the limited data resolution. A recent theoretical approach [Altomare, Cuocci, Giacovazzo, Kamel, Moliterni & Rizzi (2008). Acta Cryst. A64, 326-336] suggests that the resolution bias may be reduced by correcting the current electron density maps in accordance with the physics of the diffraction experiment. We have implemented the approach in EXP02004 [Altomare, Caliandro, Camalli, Cuocci, Giacovazzo, Moliterni & Rizzi (2004). J. Appl. Cryst. 37, 1025-1028], a program devoted to the solution of crystal structures from powder data. The new algorithm was applied at the end of the direct methods modulus, to verify if the reduction of the resolution bias is able to improve the electron density maps and to provide additional power to direct methods. Application of this method to a large set of test structures indicates that resolution-bias correction often makes the difference between success and failure, and thus constitutes a new tool for reducing the dependence of modern crystallography on resolution effects. The chances of failure are expected to depend on the quality of the experimental data (e.g. the accuracy of the fullpattern decomposition procedure and the data resolution), on the size of the structure and on its chemical composition. [ABSTRACT FROM AUTHOR]

The solution of crystal structures from powder data using direct methods can be very difficult if the quality of the diffraction pattern is low and if no heavy atoms are present in the molecule. On the contrary, the use of direct-space methods does not require good quality diffraction data, but if a molecular model is available, the structure solution is limited principally by the number of degrees of freedom used to describe the model. The combination of the information contained in the electron density map (direct methods) with the Monte Carlo method, which uses simulated annealing as a global minimization algorithm (direct-space techniques), can be a useful tool for crystal structure solution, especially for organic structures. A modified and improved version of this approach [Altomare et al. (2003), J. Appi. Cryst. 36, 230-238J has been implemented in the EXPO2004 program and is described here. [ABSTRACT FROM AUTHOR]

The space-group determination process by powder diffraction data is not straightforward. The low accuracy of the reflection intensities may invalidate the calculation of the probability associated to each extinction group that is compatible with the crystal system determined in the indexation step. Here the combination of the z statistics with two new algorithms is reported: the first checks the quality of each 2θ interval in order to omit doubtful z estimates from the calculations; the second creates a list of reflections with peaks that weakly overlap with any other peak, in order to check if any of them violates the extinction rules of the extinction symbol. The new approach has been applied to a large set of test structures and proved to be much more efficient than the procedure based only on the z statistics. [ABSTRACT FROM AUTHOR]

The electron density map produced after the application of direct methods to powder diffraction data of organic compounds is usually very approximated: some atoms are missed, other atoms are in false positions, some atoms are imperfectly located and the connectivity is quite low. A new procedure able to recover the complete structure model is described. In this procedure, a better interpretation of the map is combined with geometrical techniques for generating new atomic positions. The application of the new procedure may lead to the recovery of the complete crystal structure. [ABSTRACT FROM AUTHOR]

The Rietveld method is the most widely used approach for refining crystal structures from powder diffraction patterns. It requires sufficiently accurate structure models and user skill. A method is described which is often able to complete and refine a structure model by using an automatic least-squares procedure applicable to reflection integrated intensities. A weighting scheme has been devised that is capable of taking into account the lower accuracy of the estimates of the overlapping reflections. [ABSTRACT FROM AUTHOR]

The success of ab initio crystal structure solution by powder diffraction data is strictly related to the quality of the integrated intensity estimates. A new method that is able to improve the pattern decomposition step has been developed. It combines the inversion of a suitably modified Patterson map with the use of the Hamming codes [13,10] and [40,36] in order to explore more decomposition trials. The new approach has been introduced in EXPO2005, an updated version of EXPO2004, and successfully applied to a set of known organic and inorganic structures. [ABSTRACT FROM AUTHOR]

In the ideal process for crystal structure solution, the determination of the space group usually follows the indexation step. When powder data are used, peak overlap, background definition and possible impurity peaks may hinder the identification of the correct extinction group. The recent automatic procedure implemented in EXPO2004 has been further developed; the modifications are based on additional statistical criteria, with new algorithms for a better definition of the background and for the removal of impurity peaks. The new version also offers a more powerful graphical interface. Failures occur rarely, as shown by examples. [ABSTRACT FROM AUTHOR]

EXP02004 is the updated version of the EXPO program [Altomare et al. (1999). Z AppL Cryst. 32, 339–340]. The traditional steps of the ab initio powder solution process are performed automatically: indexing, space-group determination, decomposition of the pattern for extracting the observed structure-factor moduli, structure solution by direct methods, model refinement by Rietveld technique. Special strategies may be applied to improve both the estimates of the extracted structure-factor moduli and the quality of the structure model. In addition, the use of special procedures exploiting available supplementary information on molecular geometry can be successfully adopted. The graphical interface has also been improved. [ABSTRACT FROM AUTHOR]

Experimental powder diffraction diagrams, once indexed and decomposed into single diffraction intensities, can be submitted to statistical analysis for the determination of space-group symmetry. A new algorithm is illustrated, which is able to provide, on a quantitative basis, a probability value for each extinction symbol compatible with the previously established lattice symmetry. The algorithm has been implemented in EXPO2004 [Altomare, Caliandro, Camalli, Cuocci, Giacovazzo, Moliterni & Rizzi (2004) J. Appl. Cryst. 37, 1025–1028] and has been successfully tested using a large set of experimental data. [ABSTRACT FROM AUTHOR]

The decomposition of a powder diffraction pattern consists of the extraction of the intensities of the individual reflections from the experimental profile. The process is crucial for structure determination from powder diffraction data, but its accuracy is limited by the intrinsic peak overlap. A substantial improvement is achieved by considering clusters of reflections in strong overlap and partitioning in a systematic way the total intensity of each cluster among the constituent reflections. In this paper, error-correcting codes are used to explore the set of decomposition trials obtained by combining the partitions of various clusters of overlapping reflections. Linear ternary codes resulting from modifications of the Hamming codes [13, 10] and [40, 36] have been considered as the most suited for the present problem. They have been included in the EXPO program via their generator matrices. Tests on a set of experimental powder patterns show that an efficient decomposition procedure consists of performing only 27 decomposition trials, determined as the codewords of an [ndoub, 3] code, where ndoub is the number of doublets of strong overlapping reflections found in the experimental profile. This allows a reduction in the number of trials, thus processing about 2% of the number used in a previous design of the same procedure, leading to a reduction of the total execution time by nearly the same amount. [ABSTRACT FROM AUTHOR]

Ab inito crystal structure solution from powder diffraction data can be attained by means of the two-stage method: first the integrated intensities of the individual reflections are extracted from the experimental profile; then the extracted intensities are processed by direct methods to recover their phase. The efficiency of the direct-methods process is strongly affected by the accuracy of the extracted intensities and this is a serious drawback for the solution of organic compounds, where the presence of light atoms leads to a rapid decrease of the scattering at high angles. In order to overcome this problem, a procedure is proposed which generates a set of different intensity partitions for groups of reflections in strong overlap: the resulting decomposition trials are supplied to direct methods. the procedure is able to reduce the phase error at the end of the phasing process by up to 50° and enables the solution of organic structures with data resolution not worse than 1.5 Å in a reasonable computing time. The procedure has been implemented in the EXPO program, which makes use of the Le Bail extraction algorithm. [ABSTRACT FROM AUTHOR]

The ab initio crystal structure solution from powder diffraction data can be attempted via direct methods. If heavy atoms are present, they are usually correctly located; then some crystal chemical information can be exploited to complete the partial structure model. Organic structures are more resistant to direct methods; as an alternative, their molecular geometry is used as prior information for Monte Carlo methods. In this paper, a new procedure is described which combines the information contained in the electron density map provided by direct methods with a Monte Carlo method which uses simulated annealing as a minimization algorithm. A figure of merit has been designed based on the agreement between the experimental and calculated profiles, and on the positions of the peaks in the electron density map. The procedure is completely automatic and has been included in EXPO; its performance has been validated and tested for a set of known molecular structures. [ABSTRACT FROM AUTHOR]

Describes a method for locating missing cations and surrounding anions when the cation coordination is tetrahedral or octahedral. Aim of completing a partial structure model provided by direct methods; Use of prior information on the polyhedral coordination of the located atoms and their connectivity.

Focuses on the peak labelling of electron density. Refinement of crystal structure; Impact of incorrect labelling on crystal structure; Representation of the electron density.

Presents a random procedure for the decomposition of a powder pattern. Lack of accuracy in Bragg integrated intensity estimates; Tool for solving crystal structures; Accuracy of the integrated intensities.

Examines the completion of crystal structures from powder data through the use of the coordination polyhedra in Italy. Application of methods to powder diffraction data; Location of heavy atoms; Description of Monte Carlo procedure.

Examines the code associated to the program N-TREOR in order to define an efficient peak search procedure. Techniques used for the indexing of a powder diffraction pattern; Modification of the crystallographic decisions; Availability of N-TREOR as a stand-alone program.

The probability distribution of the structure factors with, non-integral indices is derived in P&1macr;. For integral values of at least one of the indices, the intensity distribution coincides with that provided by Wilson's statistics, but may strongly differ when the indices are (or are close to) half-integers. The deviations are stronger when the integral part of the indices is small, and increase with the size of the structure. In favourable circumstances. moduli and phases of the reflections may be accurately estimated. [ABSTRACT FROM AUTHOR]

QUALX is a new computer program for phase identification using powder diffraction data. It uses the Powder Diffraction File database, where a search for the phase best matching the experimental powder diffraction pattern is carried out. The program is characterized by a high level of automation: the traditional steps aimed at interpreting the experimental pattern before the search (background estimation, peak search, peak intensity evaluation) are executed automatically. The search may be carried out via constraints on compound name and/or chemical elements. In addition, several graphical options requested interactively enable the user to perform zero point correction evaluation, Kα2 stripping and smoothing. The program, written in Fortran95 and C++, runs on PCs under the Windows XP operating system. It is supported by a very effective graphical interface. [ABSTRACT FROM AUTHOR]

Focuses on real-space techniques use for phase extension and refinement in the modern direct procedures for ab initio crystal structure solution of proteins. Implementation of the process in a modified version of EXPO; Ability of supplying a more complete structural model; Refinement of the model by a diagonal least-squares procedure.

Layered (2D) perovskites are an emerging attractive 2D system with enhanced stability to ambient conditions as opposed to their highly unstable three dimensional bulk counterpart. Their uniquely tuneable optical and electrical properties are underpinning a surge of interest in 2D‐photovoltaics. So far, the development of nano‐scale integrated opto‐electronic 2D perovskite devices remains nearly unexplored since they have generally been found to be incompatible with standard top‐down semiconductor nano‐fabrication technologies. Here, following the synthesis of solvent‐stable 2D‐fluorinated phenethylammonium lead iodide perovskite (F‐PEA)2PbI4 (F‐PEAI), planar photodetectors entirely fabricated in atmosphere is demonstrated, exhibiting figures of merit rivalling those of commercial silicon photodiodes. A record large room temperature detectivity (>5 × 1017 Jones), a fast time photoresponse (rise time 1.5 ns), an extraordinarily large linear dynamic range (228 dB), as well as a photo‐responsivity of ≈ 1100 AW−1 are demonstrated for devices on a range of substrates including flexible wearable media without the need for any planarization or any atomically thin dielectric, in stark contrast to other 2D semiconductors. Finally, the suitability of nano‐scale 2D F‐PEAI photodetector arrays with sub‐wavelength pixel size of just 100 nm of use for high definition imaging is demonstrated. [ABSTRACT FROM AUTHOR]

The structure of the title compound, (C10H12N2)[SnF3]2, is made up of alternating layers of cations and anions, where the anion layers form extended polymeric sheets through a series of secondary Sn...F bonds. Strong N—H...F hydrogen bonds crosslink adjacent cation and anion layers, thereby building a three-dimensional network. [ABSTRACT FROM AUTHOR]

The title compound, C24H25NO3·2CH3OH, which crystallized as a methanol disolvate, has applications as a PET radiotracer in the early diagnosis of Alzheimer's disease. The dihedral angle between the biphenyl rings is 8.2 (2)° and the heterocyclic ring adopts a half-chair conformation with the N atom adopting a pyramidal geometry (bond-angle sum = 327.6°). The C atoms of both meth-oxy groups lie close to the plane of their attached ring [deviations = 0.107 (6) and 0.031 (6) Å]. In the crystal, the components are linked by O-H⋯O and O-H⋯N hydrogen bonds, generating [010] chains. C-H⋯O inter-actions are also observed.

Dibarium micro-oxido-bis[pentachloridoruthenate(IV)] decahydrate, Ba(2)Ru(2)Cl(10)O.10H(2)O, has been prepared from ruthenium(III) chloride and barium chloride in hydrochloric acid. It crystallizes in the monoclinic system (space group C2/c). The structure consists of alternating layers of [Ru(2)Cl(10)O](4-) and [Ba(H(2)O)(7)](2+) complex ions along the a direction. The O atom bonded to ruthenium occupies the 4e site, with 1 symmetry, while the other atoms occupy general 8f sites. The overall structure is held together by O-H...O hydrogen bonds and O-H...Cl dipole-dipole interactions.

Mg2Ru2Cl10O.16H2O {dimagnesium mu-oxo-bis[pentachlororuthenate(IV)] hexadecahydrate} crystallizes in the monoclinic system (space group P2(1)/c). The structure consists of layers of [Ru2Cl10O]4- anions, [Mg(H2O)6]2+ cations and water molecules stacked along the a axis. Only the O atom bonded to Ru occupies the 2a site with -1 symmetry. All the other atoms occupy general 4e sites. The crystal structure is stabilized by O-H...O and O-H...Cl interactions.