Structural characterization of a hybrid terpyridine–pyrazine ligand and its one‐dimensional ZnII coordination polymer: a computational approach to conventional and nonconventional intermolecular interactions

The structures of a new hybrid terpyridine–pyrazine ligand, namely 4′‐[4‐(pyrazin‐2‐yl)phenyl]‐4,2′:6′,4′′‐terpyridine (L2), C₂₅H₁₇N₅, and its one‐dimensional coordination polymer catena‐poly[[bis(acetylacetonato‐κ²O,O′)zinc]‐μ‐4′‐[4‐(pyrazin‐2‐yl‐κN⁴)phenyl]‐4,2′:6′,4′′‐terpyridine‐κN¹], [Zn(C₅H₇O₂)₂(C₂₅H₁₇N₅)]_n or [Zn(acac)₂(L2)]_n (Hacac is acetylacetone), are reported. Packing interactions in both crystal structures are analyzed using Hirshfeld surface and enrichment ratio techniques. For the simpler structure of the monomeric ligand, further studies on the interaction hierarchy using the energy framework approach were made. The result was a complete picture of the intermolecular interaction landscape, which revealed some subtle details, for example, that some weak (at first sight negligible) C—H…N interactions in the structure of free L2 play a relevant role in the crystal stabilization.     

A new luminescent anionic metal–organic framework based on heterometallic zinc(II)–barium(II) for selective detection of Fe3+ and Cu2+ ions in aqueous solution

Over the past two decades, the development of novel inorganic–organic hybrid porous crystalline materials or metal–organic frameworks (MOFs) using crystal engineering has provoked significant interest due to their potential applications as functional materials. In this context, luminescent MOFs as fluorescence sensors have recently received significant attention for the sensing of ionic species and small molecules. In this work, a new luminescent heterometallic zinc(II)–barium(II)‐based anionic metal–organic framework, namely poly[imidazolium [triaqua(μ₆‐benzene‐1,3,5‐tricarboxylato)bariumtrizinc] tetrahydrate], {(C₃H₄N₂)[BaZn₃(C₉H₃O₆)₃(H₂O)₃]·4H₂O}_n ( 1 ), was synthesized under hydrothermal conditions and characterized. Compound 1 presents a three‐dimensional framework with an unprecedented (3,5)‐connected topology of the point symbol (3.9²).(3³.4².5.9³.10), and exhibits `turn‐off' luminescence responses for the Cu²⁺ and Fe³⁺ ions in aqueous solution based on significantly different quenching mechanisms.     

Adsorption behaviour of a CdII–triazole MOF for butan‐2‐one in a single‐crystal‐to‐single‐crystal (SCSC) fashion: the role of hydrogen bonding and C—H…π interactions

The adsorption behaviour of the Cd^II–MOF {[Cd(L)₂(ClO₄)₂]·H₂O ( 1 ), where L is 4‐amino‐3,5‐bis[3‐(pyridin‐4‐yl)phenyl]‐1,2,4‐triazole, for butan‐2‐one was investigated in a single‐crystal‐to‐single‐crystal (SCSC) fashion. A new host–guest system that encapsulated butan‐2‐one molecules, namely poly[[bis{μ₃‐4‐amino‐3,5‐bis[3‐(pyridin‐4‐yl)phenyl]‐1,2,4‐triazole}cadmium(II)] bis(perchlorate) butanone sesquisolvate], {[Cd(C₂₄H₁₈N₆)₂](ClO₄)₂·1.5C₄H₈O}_n, denoted C₄H₈O@Cd‐MOF ( 2 ), was obtained via an SCSC transformation. MOF 2 crystallizes in the tetragonal space group P4₃2₁2. The specific binding sites for butan‐2‐one in the host were determined by single‐crystal X‐ray diffraction studies. N—H…O and C—H…O hydrogen‐bonding interactions and C—H…π interactions between the framework, ClO₄^? anions and guest molecules co‐operatively bind 1.5 butan‐2‐one molecules within the channels. The adsorption behaviour was further evidenced by ¹H NMR, IR, TGA and powder X‐ray diffraction experiments, which are consistent with the single‐crystal X‐ray analysis. A ¹H NMR experiment demonstrates that the supramolecular interactions between the framework, ClO₄^? anions and guest molecules in MOF 2 lead to a high butan‐2‐one uptake in the channel.     

Ni-Co@C-N催化剂的制备及其催化硝基芳烃还原偶联反应

以ZIF-67为前驱体,通过高温热解和乙二醇还原的方法制备了低成本的负载镍纳米粒子催化剂Ni-Co@C-N。研究了催化剂对硝基芳烃化合物合成相应氧化偶氮苯类化合物的催化性能,并讨论了碱及分散剂种类对催化剂结构与性能的影响。结果表明,碱性增强可以加快纳米粒子的成核速率,分散剂分子量增加则会限制纳米粒子的粒径增长。其中,由弱碱与低分子量分散剂制备的Ni-Co@C-N-4对硝基芳烃还原具有良好的催化活性,原料的转化率和产率在反应30 min后分别达到92.8%和89.3%,且循环实验表明Ni-Co@C-N-4具有良好的稳定性。     

一种镉基金属有机骨架材料对丙酮和Fe3+的荧光检测

以1,3,5-三（4-羧基苯基）苯（H₃BTB）为配体,通过溶剂热法得到一种三维四重穿插结构的镉基金属有机骨架材料：（Me₂NH₂）[Cd（BTB）（DMF）]·DMF·H₂O（Cd-MOF）。通过单晶X射线衍射、粉末X射线衍射、红外分析、元素分析和热重分析表征了其组成和结构。荧光研究结果表明：Cd-MOF在含有丙酮或Fe³⁺离子的溶液中均表现出荧光猝灭现象,其检测限（体积分数和浓度）分别为0.6%和0.89 μmol·L^-1,线性检测范围分别为2.0%~2.8%和0~0.05 mmol·L^-1。时间响应实验和可循环利用实验显示Cd-MOF可长时间、稳定且高效地检测丙酮和Fe³⁺离子。     

一种可复用的网络社交游戏开发框架设计

采用应用开发框架技术,提出一种可复用的网络社交游戏应用框架,避免底层关键技术的重复开发。利用该框架开发1个网络社交游戏游戏并上线运营,实践表明该框架的架构的可伸缩性、可用性较好,可以缩短开发周期。     

Struts2框架的改进与实现

为提高Web应用开发效率,在进一步改进MVC模式的实现框架Struts2的基础上,设计轻量级模块化Web应用基础框架.应用实践表明:该框架可应用于各种复杂Web应用,具有开发速度快、管理方便、过程严谨、易于部署的特点,可较好地规范开发流程,保障开发质量.     

基于信息处理的藏文框架语义关系研究

藏文框架语义知识语义关系分析的关键就是建立句子中各词语之间的语义关联关系,实现各框架间知识的共享,获取更多的信息.文章引出了藏文框架语义知识、框架及框架元素并结合实例分析了以藏语句子为主,组成该句子的词语或短语间的语义关系及框架形式表示该句子的语义为结构化.     

开源大数据框架在海洋信息处理中的应用

 随着中国海洋观测技术和数据收集手段的发展,海洋观测数据量日益庞大、数据复杂程度逐渐增多,传统的数据存储方式和处理方法无法有效地对海洋数据进行管理和分析,同时,数据的区域化和分布化成为海洋数据统一管理的一个障碍,对海洋数据挖掘造成一定困难。本文从大数据生命周期的维度,介绍了主流开源大数据框架在海洋大数据获取、存储、处理、智能分析、安全保护和治理方面的技术原理和应用。     

Infrared small target tracking based on sample constrained particle filtering and sparse representation

Infrared search and track technology for small target plays an important role in infrared warning and guidance. In view of the tacking randomness and uncertainty caused by background clutter and noise interference, a robust tracking method for infrared small target based on sample constrained particle filtering and sparse representation is proposed in this paper. Firstly, to distinguish the normal region and interference region in target sub-blocks, we introduce a binary support vector, and combine it with the target sparse representation model, after which a particle filtering observation model based on sparse reconstruction error differences between sample targets is developed. Secondly, we utilize saliency extraction to obtain the high frequency area in infrared image, and make it as a priori knowledge of the transition probability model to limit the particle filtering sampling process. Lastly, the tracking result is brought about via target state estimation and the Bayesian posteriori probability calculation. Theoretical analyses and experimental results show that our method can enhance the state estimation ability of stochastic particles, improve the sparse representation adaptabilities for infrared small targets, and optimize the tracking accuracy for infrared small moving targets.