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Crystals, Volume 6, Issue 5 (May 2016)

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Editorial

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Open AccessEditorial Analysis of Hydrogen Bonds in Crystals
Crystals 2016, 6(5), 59; doi:10.3390/cryst6050059
Received: 12 May 2016 / Revised: 12 May 2016 / Accepted: 13 May 2016 / Published: 17 May 2016
Cited by 2 | PDF Full-text (940 KB) | HTML Full-text | XML Full-text
Abstract
The determination of crystal structures provides important information on the geometry of species constituting crystals and on the symmetry relations between them. Additionally, the analysis of crystal structures is so conclusive that it allows us to understand the nature of various interactions. The
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The determination of crystal structures provides important information on the geometry of species constituting crystals and on the symmetry relations between them. Additionally, the analysis of crystal structures is so conclusive that it allows us to understand the nature of various interactions. The hydrogen bond interaction plays a crucial role in crystal engineering and, in general, its important role in numerous chemical, physical and bio-chemical processes was the subject of various studies. That is why numerous important findings on the nature of hydrogen bonds concern crystal structures. This special issue presents studies on hydrogen bonds in crystals, and specific compounds and specific H-bonded patterns existing in crystals are analyzed. However, the characteristics of the H-bond interactions are not only analyzed theoretically; this interaction is compared with other ones that steer the arrangement of molecules in crystals, for example halogen, tetrel or pnicogen bonds. More general findings concerning the influence of the hydrogen bond on the physicochemical properties of matter are also presented. Full article
(This article belongs to the Special Issue Analysis of Hydrogen Bonds in Crystals) Printed Edition available

Research

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Open AccessArticle The Role of Coulomb Interactions for Spin Crossover Behaviors and Crystal Structural Transformation in Novel Anionic Fe(III) Complexes from a π-Extended ONO Ligand
Crystals 2016, 6(5), 49; doi:10.3390/cryst6050049
Received: 30 March 2016 / Revised: 27 April 2016 / Accepted: 28 April 2016 / Published: 3 May 2016
Cited by 3 | PDF Full-text (3129 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
To investigate the π-extension effect on an unusual negative-charged spin crossover (SCO) FeIII complex with a weak N2O4 first coordination sphere, we designed and synthesized a series of anionic FeIII complexes from a π-extended naphthalene derivative ligand. Acetonitrile-solvate
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To investigate the π-extension effect on an unusual negative-charged spin crossover (SCO) FeIII complex with a weak N2O4 first coordination sphere, we designed and synthesized a series of anionic FeIII complexes from a π-extended naphthalene derivative ligand. Acetonitrile-solvate tetramethylammonium (TMA) salt 1 exhibited an SCO conversion, while acetone-solvate TMA salt 2 was in a high-spin state. The crystal structural analysis for 2 revealed that two-leg ladder-like cation-anion arrays derived from π-stacking interactions between π-ligands of the FeIII complex anion and Coulomb interactions were found and the solvated acetone molecules were in one-dimensional channels between the cation-anion arrays. A desolvation-induced single-crystal-to-single-crystal transformation to desolvate compound 2’ may be driven by Coulomb energy gain. Furthermore, the structural comparison between quasi-polymorphic compounds 1 and 2 revealed that the synergy between Coulomb and π-stacking interactions induces a significant distortion of coordination structure of 2. Full article
(This article belongs to the Special Issue High Spin Molecules)
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Open AccessArticle Broadband Transmission Loss Using the Overlap of Resonances in 3D Sonic Crystals
Crystals 2016, 6(5), 51; doi:10.3390/cryst6050051
Received: 25 March 2016 / Revised: 25 April 2016 / Accepted: 3 May 2016 / Published: 11 May 2016
Cited by 2 | PDF Full-text (824 KB) | HTML Full-text | XML Full-text
Abstract
The acoustic properties of a three-dimensional sonic crystal made of square-rod rigid scatterers incorporating a periodic arrangement of quarter wavelength resonators are theoretically and experimentally reported in this work. The periodicity of the system produces Bragg band gaps that can be tuned in
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The acoustic properties of a three-dimensional sonic crystal made of square-rod rigid scatterers incorporating a periodic arrangement of quarter wavelength resonators are theoretically and experimentally reported in this work. The periodicity of the system produces Bragg band gaps that can be tuned in frequency by modifying the orientation of the square-rod scatterers with respect to the incident wave. In addition, the quarter wavelength resonators introduce resonant band gaps that can be tuned by coupling the neighbor resonators. Bragg and resonant band gaps can overlap allowing the wave propagation control inside the periodic resonant medium. In particular, we show theoretically and experimentally that this system can produce a broad frequency band gap exceeding two and a half octaves (from 590 Hz to 3220 Hz) with transmission lower than 3%. Finite element methods were used to calculate the dispersion relation of the locally resonant system. The visco-thermal losses were accounted for in the quarter wavelength resonators to simulate the wave propagation in the semi-infinite structures and to compare the numerical results with the experiments performed in an echo-free chamber. The simulations and the experimental results are in good agreement. This work motivates interesting applications of this system as acoustic audible filters. Full article
(This article belongs to the Special Issue Phononic Crystals)
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Open AccessArticle Formation of Bragg Band Gaps in Anisotropic Phononic Crystals Analyzed With the Empty Lattice Model
Crystals 2016, 6(5), 52; doi:10.3390/cryst6050052
Received: 25 March 2016 / Revised: 25 April 2016 / Accepted: 3 May 2016 / Published: 11 May 2016
Cited by 3 | PDF Full-text (3801 KB) | HTML Full-text | XML Full-text
Abstract
Bragg band gaps of phononic crystals generally, but not always, open at Brillouin zone boundaries. The commonly accepted explanation stems from the empty lattice model: assuming a small material contrast between the constituents of the unit cell, avoided crossings in the phononic band
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Bragg band gaps of phononic crystals generally, but not always, open at Brillouin zone boundaries. The commonly accepted explanation stems from the empty lattice model: assuming a small material contrast between the constituents of the unit cell, avoided crossings in the phononic band structure appear at frequencies and wavenumbers corresponding to band intersections; for scalar waves the lowest intersections coincide with boundaries of the first Brillouin zone. However, if a phononic crystal contains elastically anisotropic materials, its overall symmetry is not dictated solely by the lattice symmetry. We construct an empty lattice model for phononic crystals made of isotropic and anisotropic materials, based on their slowness curves. We find that, in the anisotropic case, avoided crossings generally do not appear at the boundaries of traditionally defined Brillouin zones. Furthermore, the Bragg “planes” which give rise to phononic band gaps, are generally not flat planes but curved surfaces. The same is found to be the case for avoided crossings between shear (transverse) and longitudinal bands in the isotropic case. Full article
(This article belongs to the Special Issue Phononic Crystals)
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Open AccessArticle Comparisons between Crystallography Data and Theoretical Parameters and the Formation of Intramolecular Hydrogen Bonds: Benznidazole
Crystals 2016, 6(5), 56; doi:10.3390/cryst6050056
Received: 1 February 2016 / Revised: 29 April 2016 / Accepted: 4 May 2016 / Published: 12 May 2016
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Abstract
The conformational preferences of benznidazole were examined through the application of DFT, PCM and QTAIM calculations, whose results were compared with crystallography data. The geometries were fully optimized with minimum potential energy surface by means of the Relaxed Potential Energy Surface Scan (RPESS)
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The conformational preferences of benznidazole were examined through the application of DFT, PCM and QTAIM calculations, whose results were compared with crystallography data. The geometries were fully optimized with minimum potential energy surface by means of the Relaxed Potential Energy Surface Scan (RPESS) at AM1, followed by the B3LYP/6-311++G(d,p) theoretical level. As a result, the s-cis conformation (1C) was shown to be more stable (4.78 kcal∙mol−1) than s-trans (1T). The Quantum Theory Atoms in Molecules (QTAIM) was applied in order to characterize the (N–H∙∙∙O=N) and (C–H∙∙∙=N) intramolecular hydrogen bonds. The simulation of solvent effect performed by means of the implicit Polarized Continuum Model (PCM) revealed great results, such as, for instance, that the conformation 1W is more stable (23.17 kcal∙mol−1) in comparison to 1C. Our main goal was stressed in the topological description of intramolecular hydrogen bonds in light of the QTAIM approach, as well as in the solvent simulation to accurately obtain an important conformation of benznidazole. Full article
(This article belongs to the Special Issue Analysis of Hydrogen Bonds in Crystals) Printed Edition available
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Open AccessArticle The Synthesis and Crystal Structure of Two New Hydrazone Compounds
Crystals 2016, 6(5), 57; doi:10.3390/cryst6050057
Received: 18 March 2016 / Revised: 18 April 2016 / Accepted: 12 May 2016 / Published: 17 May 2016
Cited by 2 | PDF Full-text (1562 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Two new hydrazone compounds, 4-formylimidazole-4-hydroxybenzhydrazone dihydrate (1) and 2-nitrobenzaldehyde-2-furan formylhydrazone (2), were synthesized via the classical synthesis method. Their structure was determined via elemental analysis and X-ray single crystal diffraction analysis. Compound 1 crystallizes in triclinic, space group P-1 with a =
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Two new hydrazone compounds, 4-formylimidazole-4-hydroxybenzhydrazone dihydrate (1) and 2-nitrobenzaldehyde-2-furan formylhydrazone (2), were synthesized via the classical synthesis method. Their structure was determined via elemental analysis and X-ray single crystal diffraction analysis. Compound 1 crystallizes in triclinic, space group P-1 with a = 7.0321(14) Å, b = 7.3723(15) Å, c = 13.008(3) Å, α = 98.66(3)°, β = 101.69(3)°, γ = 92.25(3)°, V = 651.2(2) Å3, Z = 2, Dc = 1.358 g·cm−3, μ = 0.106 mm−1, F(000) = 280, and final R1 = 0.0564, wR2 = 0.1420. Compound 2 crystallizes in monoclinic, space group P21/c with a = 17.3618(9) Å, b = 9.1506(4) Å, c = 15.5801(7) Å, β = 104.532(5)°, V = 2396.05(19) Å3, Z = 8, Dc = 1.437 g·cm−3, μ = 0.111 mm−1, F(000) = 1072, and final R1 = 0.0633, wR2 = 0.1649. Compound 1 forms a 2D-layered structure via the interactions of 1D chains and Compound 2 forms a 3D network structure via the interactions of 1D chains. Full article
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Open AccessArticle Colloidal Photonic Crystals Containing Silver Nanoparticles with Tunable Structural Colors
Crystals 2016, 6(5), 61; doi:10.3390/cryst6050061
Received: 13 April 2016 / Revised: 12 May 2016 / Accepted: 17 May 2016 / Published: 19 May 2016
Cited by 5 | PDF Full-text (4616 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Polystyrene (PS) colloidal photonic crystals (CPhCs) containing silver nanoparticles (AgNPs) present tunable structural colors. PS CPhC color films containing a high concentration of AgNPs were prepared using self-assembly process through gravitational sedimentation method. High-concentration AgNPs were deposited on the bottom of the substrate
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Polystyrene (PS) colloidal photonic crystals (CPhCs) containing silver nanoparticles (AgNPs) present tunable structural colors. PS CPhC color films containing a high concentration of AgNPs were prepared using self-assembly process through gravitational sedimentation method. High-concentration AgNPs were deposited on the bottom of the substrate and acted as black materials to absorb background and scattering light. Brilliant structural colors were enhanced because of the absorption of incoherent scattering light, and color saturation was increased by the distribution AgNPs on the PS CPhC surfaces. The vivid iridescent structural colors of AgNPs/PS hybrid CPhC films were based on Bragg diffraction and backward scattering absorption using AgNPs. The photonic stop band of PS CPhCs and AgNPs/PS hybrid CPhCs were measured by UV–visible reflection spectrometry and calculated based on the Bragg–Snell law. In addition, the tunable structural colors of AgNPs/PS hybrid CPhC films were evaluated using color measurements according to the Commission International d’Eclairage standard colorimetric system. This paper presents a simple and inexpensive method to produce tunable structural colors for numerous applications, such as textile fabrics, bionic colors, catalysis, and paints. Full article
(This article belongs to the Special Issue Colloidal Crystals)
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Open AccessArticle Influence of Defects in Boron Nitride Nanotubes in the Adsorption of Molecules. Insights from B3LYP-D2* Periodic Simulations
Crystals 2016, 6(5), 63; doi:10.3390/cryst6050063
Received: 27 April 2016 / Revised: 11 May 2016 / Accepted: 12 May 2016 / Published: 20 May 2016
Cited by 9 | PDF Full-text (1678 KB) | HTML Full-text | XML Full-text
Abstract
The adsorption of H2O, NH3 and HCOOH as polar molecules and C6H6 and CH4 as non-polar ones on a series of zig-zag (6,0) single-walled boron nitride nanotubes (BNNTs) both being defect-free (P_BNNT) and containing defects at
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The adsorption of H2O, NH3 and HCOOH as polar molecules and C6H6 and CH4 as non-polar ones on a series of zig-zag (6,0) single-walled boron nitride nanotubes (BNNTs) both being defect-free (P_BNNT) and containing defects at the nanotube walls has been studied by means of B3LYP-D2* periodic calculations. We focused on defects derived from monovacancies of B (N-rich_BNNT) and N (B-rich_BNNT) atoms and also on Stone-Wales defects (SW_BNNT). The adsorption of polar molecules with defective BNNTs is generally based on dative interactions and H-bonding, and their adsorption energies strongly depend on the type of BNNT. N-rich_BNNT is the most reactive nanotube towards adsorption of polar molecules, as in all cases deprotonation of the polar molecules is spontaneously given upon adsorption. The strength in the adsorption energies is followed by B-rich_BNNT, SW_BNNT and P_BNNT. Adsorption of non-polar molecules is mainly dictated by dispersion interactions, and, accordingly, the adsorption energies are almost constant for a given molecule irrespective of the type of nanotube. Full article
(This article belongs to the Special Issue Boron-Based (Nano-)Materials: Fundamentals and Applications)
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Review

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Open AccessReview Coordination Networks Based on Boronate and Benzoxaborolate Ligands
Crystals 2016, 6(5), 48; doi:10.3390/cryst6050048
Received: 29 March 2016 / Revised: 20 April 2016 / Accepted: 27 April 2016 / Published: 2 May 2016
Cited by 1 | PDF Full-text (3990 KB) | HTML Full-text | XML Full-text
Abstract
Despite the extensive range of investigations on boronic acids (R-B(OH)2), some aspects of their reactivity still need to be explored. This is the case for the coordination chemistry of boronate anions (R-B(OH)3), which has only recently been started
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Despite the extensive range of investigations on boronic acids (R-B(OH)2), some aspects of their reactivity still need to be explored. This is the case for the coordination chemistry of boronate anions (R-B(OH)3), which has only recently been started to be studied. The purpose of this review is to summarize some of the key features of boronate ligands (and of their cyclic derivatives, benzoxaborolates) in materials: (i) coordination properties; (ii) spectroscopic signatures; and (iii) emerging applications. Full article
(This article belongs to the Special Issue Boron-Based (Nano-)Materials: Fundamentals and Applications)
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Open AccessReview N,O-Type Carborane-Based Materials
Crystals 2016, 6(5), 50; doi:10.3390/cryst6050050
Received: 29 March 2016 / Revised: 25 April 2016 / Accepted: 27 April 2016 / Published: 4 May 2016
Cited by 4 | PDF Full-text (8083 KB) | HTML Full-text | XML Full-text
Abstract
This review summarizes the synthesis and coordination chemistry of a series of carboranyl ligands containing N,O donors. Such carborane-based ligands are scarcely reported in the literature when compared to other heteroatom-containing donors. The synthetic routes for metal complexes of these N,O-type carborane ligands
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This review summarizes the synthesis and coordination chemistry of a series of carboranyl ligands containing N,O donors. Such carborane-based ligands are scarcely reported in the literature when compared to other heteroatom-containing donors. The synthetic routes for metal complexes of these N,O-type carborane ligands are summarized and the properties of such complexes are described in detail. Particular attention is paid to the effect that the incorporation of carboranes has into the coordination chemistry of the otherwise carbon-based ligands and the properties of such materials. The reported complexes show a variety of properties such as those used in magnetic, chiroptical, nonlinear optical, catalytic and biomedical applications. Full article
(This article belongs to the Special Issue Boron-Based (Nano-)Materials: Fundamentals and Applications)
Open AccessReview Epitaxial Graphene on SiC: A Review of Growth and Characterization
Crystals 2016, 6(5), 53; doi:10.3390/cryst6050053
Received: 19 February 2016 / Revised: 11 April 2016 / Accepted: 28 April 2016 / Published: 12 May 2016
Cited by 12 | PDF Full-text (23138 KB) | HTML Full-text | XML Full-text
Abstract
This review is devoted to one of the most promising two-dimensional (2D) materials, graphene. Graphene can be prepared by different methods and the one discussed here is fabricated by the thermal decomposition of SiC. The aim of the paper is to overview the
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This review is devoted to one of the most promising two-dimensional (2D) materials, graphene. Graphene can be prepared by different methods and the one discussed here is fabricated by the thermal decomposition of SiC. The aim of the paper is to overview the fabrication aspects, growth mechanisms, and structural and electronic properties of graphene on SiC and the means of their assessment. Starting from historical aspects, it is shown that the most optimal conditions resulting in a large area of one ML graphene comprise high temperature and argon ambience, which allow better controllability and reproducibility of the graphene quality. Elemental intercalation as a means to overcome the problem of substrate influence on graphene carrier mobility has been described. The most common characterization techniques used are low-energy electron microscopy (LEEM), angle-resolved photoelectron spectroscopy (ARPES), Raman spectroscopy, atomic force microscopy (AFM) in different modes, Hall measurements, etc. The main results point to the applicability of graphene on SiC in quantum metrology, and the understanding of new physics and growth phenomena of 2D materials and devices. Full article
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Open AccessReview Bottom-Up Assembly and Applications of Photonic Materials
Crystals 2016, 6(5), 54; doi:10.3390/cryst6050054
Received: 12 April 2016 / Revised: 4 May 2016 / Accepted: 9 May 2016 / Published: 12 May 2016
Cited by 3 | PDF Full-text (10483 KB) | HTML Full-text | XML Full-text
Abstract
The assembly of colloidal building-blocks is an efficient, inexpensive and flexible approach for the fabrication of a wide variety of photonic materials with designed shapes and large areas. In this review, the various assembly routes to the fabrication of colloidal crystals and their
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The assembly of colloidal building-blocks is an efficient, inexpensive and flexible approach for the fabrication of a wide variety of photonic materials with designed shapes and large areas. In this review, the various assembly routes to the fabrication of colloidal crystals and their post-assembly modifications to the production of photonic materials are first described. Then, the emerging applications of the colloidal photonic structures in various fields such as biological and chemical sensing, anti-reflection, photovoltaics, and light extraction are summarized. Full article
(This article belongs to the Special Issue Colloidal Crystals)
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Open AccessReview How to Increase the h-BN Crystallinity of Microfilms and Self-Standing Nanosheets: A Review of the Different Strategies Using the PDCs Route
Crystals 2016, 6(5), 55; doi:10.3390/cryst6050055
Received: 7 April 2016 / Revised: 1 May 2016 / Accepted: 3 May 2016 / Published: 13 May 2016
Cited by 4 | PDF Full-text (10332 KB) | HTML Full-text | XML Full-text
Abstract
Hexagonal boron nitride (h-BN) is a well-known material whose use is almost restricted to lubricating applications in domains ranging from metallurgy to cosmetics. Howover, h-BN displays many other interesting properties, opening new perspectives for other engineering applications, such as as a solid lubricant
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Hexagonal boron nitride (h-BN) is a well-known material whose use is almost restricted to lubricating applications in domains ranging from metallurgy to cosmetics. Howover, h-BN displays many other interesting properties, opening new perspectives for other engineering applications, such as as a solid lubricant in aeronautics, as the perfect substrate to graphene for electronic devices, etc. However, all these promising developments require tailored h-BN shapes displaying a high level of crystallization, ensuring its properties for the long term. Here, we developed three strategies, all associated with the Polymer Derived Ceramics (PDCs) route, to prepare highly crystallized supported thick coatings and self-standing nanosheets. The first strategy concerns the innovative implementation of a Rapid Thermal Annealing to prepare micrometric h-BN coatings on thermal sensitive substrates. Compared to conventional treatment the crystallization of h-BN has successfully lowered to about 300 °C. The second strategy consists of an additivation of the used polymer precursor. Effect of lithium nitride as a crystallization promoter was investigated lowering the onset crystallization temperature from 1400 °C (traditionally) to 1000 °C. This novel synthetic route allows preparing self-standing highly crystallized h-BN nanolayers. Finally, the third strategy is based on a unique combination of the PDCs route with Spark Plasma Sintering to profit of both approaches. This original method leads to large and well-crystallized flakes available for a subsequent exfoliation. Full article
(This article belongs to the Special Issue Boron-Based (Nano-)Materials: Fundamentals and Applications)
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Open AccessReview The Effect of Ligand Design on Metal Ion Spin State—Lessons from Spin Crossover Complexes
Crystals 2016, 6(5), 58; doi:10.3390/cryst6050058
Received: 22 April 2016 / Revised: 11 May 2016 / Accepted: 13 May 2016 / Published: 18 May 2016
Cited by 9 | PDF Full-text (5432 KB) | HTML Full-text | XML Full-text
Abstract
The relationship between chemical structure and spin state in a transition metal complex has an important bearing on mechanistic bioinorganic chemistry, catalysis by base metals, and the design of spin crossover materials. The latter provide an ideal testbed for this question, since small
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The relationship between chemical structure and spin state in a transition metal complex has an important bearing on mechanistic bioinorganic chemistry, catalysis by base metals, and the design of spin crossover materials. The latter provide an ideal testbed for this question, since small changes in spin state energetics can be easily detected from shifts in the spin crossover equilibrium temperature. Published structure-function relationships relating ligand design and spin state from the spin crossover literature give varied results. A sterically crowded ligand sphere favors the expanded metal–ligand bonds associated with the high-spin state. However, steric clashes at the molecular periphery can stabilize either the high-spin or the low-spin state in a predictable way, depending on their effect on ligand conformation. In the absence of steric influences, the picture is less clear since electron-withdrawing ligand substituents are reported to favor the low-spin or the high-spin state in different series of compounds. A recent study has shed light on this conundrum, showing that the electronic influence of a substituent on a coordinated metal ion depends on its position on the ligand framework. Finally, hydrogen bonding to complexes containing peripheral N‒H groups consistently stabilizes the low-spin state, where this has been quantified. Full article
(This article belongs to the Special Issue High Spin Molecules)
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Open AccessReview Silver and Copper Complexes with closo-Polyhedral Borane, Carborane and Metallacarborane Anions: Synthesis and X-ray Structure
Crystals 2016, 6(5), 60; doi:10.3390/cryst6050060
Received: 31 March 2016 / Revised: 19 April 2016 / Accepted: 20 April 2016 / Published: 20 May 2016
Cited by 11 | PDF Full-text (36438 KB) | HTML Full-text | XML Full-text
Abstract
Synthesis and structure of silver and copper salts and complexes with polyhedral boron hydride anions, including closo-decaborate [B10H10]2−, closo-dodecaborate [B12H12]2−, 1-carba-closo- decaborate [1-CB9H10]
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Synthesis and structure of silver and copper salts and complexes with polyhedral boron hydride anions, including closo-decaborate [B10H10]2−, closo-dodecaborate [B12H12]2−, 1-carba-closo- decaborate [1-CB9H10], carba-closo-dodecaborate [CB11H12], and cobalt bis(dicarbollide) [3,3′-Co(1,2-C2B9H11)2] anions and their derivatives, are reviewed. The complexes demonstrate a wide variety of structural types, relating to both the metal coordination environment and coordination modes of boron hydride anions. The latter can range from strong coordination via the polyhedron triangular face including formation of 3c-2e MHB bonds in the case of the [B10H10]2− dianion, the structure of which contains two four-coordinated boron atoms, to very weak M…H interactions with the hydride atoms in the case of bulky [3,3′-Co(1,2-C2B9H11)2] monoanion. Full article
(This article belongs to the Special Issue Boron-Based (Nano-)Materials: Fundamentals and Applications)
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Open AccessReview Floating Zone Growth of Bi2Sr2Ca2Cu3Oy Superconductor
Crystals 2016, 6(5), 62; doi:10.3390/cryst6050062
Received: 15 April 2016 / Accepted: 18 April 2016 / Published: 20 May 2016
Cited by 2 | PDF Full-text (3127 KB) | HTML Full-text | XML Full-text
Abstract
The crystal growth of high-temperature oxide superconductors has been hampered by the complexities of these materials and the lack of knowledge of corresponding phase diagrams. The most common crystal growth technique adopted for these materials is the so-called “Flux” method. This method, however,
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The crystal growth of high-temperature oxide superconductors has been hampered by the complexities of these materials and the lack of knowledge of corresponding phase diagrams. The most common crystal growth technique adopted for these materials is the so-called “Flux” method. This method, however, suffers from several drawbacks: (i) crystals are often crucible and flux contaminated; (ii) crystals are difficult to detach from solidified melt; and (iii) crystals are rather small. In most cases, these drawbacks can be overcome by the crucible-free floating zone method. Moreover, this technique is suitable for crystal growth of incongruently melting compounds, and has been thus successfully used to make large single crystals of Bi2Sr2Ca2Cu3Oy superconductor. In this review, the authors summarize the published and their own growth efforts as well as detailed characterization of as-grown and post-growth annealed samples. The optimal growth conditions that allowed one to obtain the large-size, almost single phase and homogeneous in composition Bi2Sr2Ca2Cu3Oy single crystals are presented. The effect of long lasting post-growth heat treatment on both crystal quality and superconducting properties has also been demonstrated. Full article
(This article belongs to the Special Issue Traveling Solvent Floating Zone (TSFZ) Method in Crystal Growth)
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