Hybrid organic–inorganic CH3NH3PbI3 perovskite building blocks: Revealing ultra‐strong hydrogen bonding and mulliken inner complexes and their implications in materials design

Methylammonium lead iodide (CH₃NH₃PbI₃) perovskite compound has produced a remarkable breakthrough in the photovoltaic history of solar cell technology because of its outstanding device‐based performance as a light‐harvesting semiconductor. Whereas the experimental and theoretical studies of this system in the solid state have been numerously reported in the last 4 years, its fundamental cluster physics is yet to be exploited. To this end, this study has performed theoretical investigations using DFT‐M06‐2X/ADZP to examine the principal geometrical, electronic, topological, and orbital properties of the CH₃NH₃PbI₃ molecular building block. The intermolecular hydrogen bonded interactions examined for the most important conformers of the system are found to be unusually strong, with binding energies lying between −93.53 and −125.11 kcal mol⁻¹ (beyond the covalent limit, −40 kcal mol⁻¹), enabling us to classify the underlying interactions as ultra‐strong type since their characteristic properties are unidentical with those have already been proposed as very strong, strong, moderate, weak, and van der Waals. Based on this, together with the unusually high charge transfers, strong hyperconjugative interactions, sophisticated topologies of the charge density, and short intermolecular distances of separation, we have characterized the conformers of CH₃NH₃PbI₃ as Mulliken inner complexes. The consequences of these, as well as of the ultra‐strong interactions, in designing novel functional nanomaterials are outlined. © 2017 Wiley Periodicals, Inc.     

密度泛函理论研究Al在丝光沸石骨架中的取代位置和NH3的吸附

采用色散校正密度泛函方法（DFT-D2）计算了Al同晶取代进入H-[Al]MOR丝光沸石骨架中可能的位置及其对NH₃分子吸附表征Brönsted酸性。热力学上,Al优先取代位是T2O5位,接着是T4O2、T1O7和T3O1位,能量差仅在0.03~0.07 eV,表明Al可能分布在四种非等价晶体T位。同时,电荷平衡质子的位置影响Al取代位的稳定性,数据表明电荷平衡质子与O5位结合的可能性最大。另外,用DFT和 DFT-D2方法计算了NH₃分子在每一个Al取代的T位的吸附能,通过比较,DFT低估了NH₃吸附能0.41 eV,表明色散校正DFT-D2方法对于NH₃吸附是很有必要的,T2O5位的Brönsted酸性最强。     

Biological Chitin–MOF Composites with Hierarchical Pore Systems for Air‐Filtration Applications

Metal–organic frameworks (MOFs) are promising materials for gas‐separation and air‐filtration applications. However, for these applications, MOF crystallites need to be incorporated in robust and manageable support materials. We used chitin‐based networks from a marine sponge as a non‐toxic, biodegradable, and low‐weight support material for MOF deposition. The structural properties of the material favor predominant nucleation of the MOF crystallites at the inside of the hollow fibers. This composite has a hierarchical pore system with surface areas up to 800 m² g⁻¹ and pore volumes of 3.6 cm³ g⁻¹, allowing good transport kinetics and a very high loading of the active material. Ammonia break‐through experiments highlight the accessibility of the MOF crystallites and the adsorption potential of the composite indicating their high potential for filtration applications for toxic industrial gases.     

NH2偶极矩的量化计算及多元线性回归的解析处理

采用GAUSSIAN98程序计算了NH2的基态的偶极矩面，采用多元线性回归 的拟合方法，由各项的线性相关性和标准偏差确定各项的取舍，得到具有合理标准偏 差的简单解析偶极矩幂级数表达式。     

稀土与邻苯二醛缩赖氨酸席夫碱配合物的合成和表征

选用具有双醛基的邻苯二醛与双氨基的赖氨酸缩合形成邻苯二醛缩赖氨酸席夫碱(HL),首次合成10种新的稀土氨基酸席夫碱配合物.在元素分析、热分析、紫外、可见、红外光谱及核磁共振谱等表征基础上,提出该类型配合物的组成为LnL2(NO3)·4H2O(Ln=La、Pr、Nd、Sm、Y)和LnL2(NO3)·3H2O(Ln=Gd、Tb、Dy、Er、Yb),研究了它们的配位机理和谱学性质,并讨论了配合物颇具特点的可能结构.     

卟啉内氢迁移反应氟取代基效应的理论研究

采用B3LYP/6-31G**的方法在Gaussian03程序下对卟吩(PH2)、m-四氟卟啉(m-TFPH2)、β-八氟卟啉(β-OFPH2)和m-四氟,β-八氟卟啉(12FPH2)的结构进行几何优化,并进行振动分析.计算并讨论了PH2、m-TFPH2、β-OFPH2和12FPH2在内氢迁移反应中的反应物、产物、中间体、过渡态及二级鞍点的结构与能量.通过对结构和能量的比较,发现各物质内氢迁移反应均以异步历程进行,可见取代基对卟啉内氢迁移反应的历程选择没有影响.但取代基会影响同步历程和异步历程之间的速率差异.另外,氟取代基使得内氢迁移反应的异步历程的正负反应速率有所减小,起决定性作用的是取代基的电子效应,这些与化学直观也是相一致的.     

Fe Promotion Effect in Mn/USY for Low-temperature Selective Catalytic Reduction of NO with NH3

SCR of NO with NH3 is considered to be the most effective process for the treatment of stack gases from stationary sources1. The commercial catalysts for NH3-SCR are V2O5/TiO2 (anatase) promoted with either WO3 or MoO32-5. Although the vanadium- based cat…     

Monitoring of the evolved gases in apatite-ammonium sulfate thermal reactions

Summary Thermal reactions in natural fluorapatite or fluorcarbonate apatite and ammonium sulfate mixtures with mole ratio 1:4 at calcination up to 500°C were studied by simultaneous thermogravimetry and FTIR analysis of the evolved gases. The composition of natural apatite has little impact on the release of NH₃. Upon the evolution of NH₃ nitrous oxides were found in minor amounts. The release of SO₂ at temperatures above 400°C is more intensive and occurs at lower temperatures in the case of fluorapatite than of carbonate containing apatites. Evolution of CO₂ starts at 250°C with maximum at 350-360°C.     

加速器质谱测量用NH4Hf2F9的制备及表征

研究了加速器质谱测量用NH4Hf2F9的制备方法,用XRD,SEM,XPS和TG-DTA表征其结构和组成.结果表明:NH4Hf2F9样品在573 K热处理1 h后物相并未变化,而在773,973,1173,1373 K热处理1 h后物相则都转变为HfO2.TG-DTA的分析表明从573 K开始NH4Hf2F9样品逐渐开始分解,至1073 K时失重约78%.样品微观形貌为不规则的固体颗粒,颗粒的粒径分布较大,范围在5～20μm之间.粉末样品主要含有Hf,N和F元素,其中Hf主要以(+4)价存在.     

Exceptional elastic anisotropy of hybrid organic–inorganic perovskite CH3NH3PbBr3 measured by laser ultrasonic technique

The results of the direct experimental evaluation of all elastic constants of single crystal hybrid organic–inorganic perovskite (HOIP) methylammonium lead bromide, a material known due to its possible solar‐energy, optoelectronics, X‐ray detector and thermoelectricity applications, are reported. The measurements of anisotropic elasticity of CH₃NH₃PbBr₃by the technique of laser ultrasonics demonstrate that properties of HOIPs can be even more remarkable than the theoretical expectations: the extracted shear modulus is more than twice smaller, the universal anisotropy is more than twice higher, while the Debye temperature is more than 50° lower. Thus HOIPs can exhibit extremely low shear rigidity and extremely high anisotropy, both strongly overrunning the parameters which have been expected based on earlier first principles theoretical predictions. A simple theoretical model of granular crystal indicates that these observations could be related to the contributions of rotations/tilts of PbBr₆octahedra to elastic response of cubic CH₃NH₃PbBr₃. Another experimental observation is strong stiffening of shear rigidity with temperature increase from its room value up to 120 °C. Discovered elastic properties of HOIPs characterize them as exceptionally ductile/flexible/adaptive materials which could be deposited on corrugated/structured surfaces. (© 2016 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)