一例对二硫化碳具有荧光传感性能的Mg-金属有机框架化合物

通过溶剂热合成了一例Mg-MOF化合物[Mg₄(1,4-NDC)₄(DMA)₂(CH₃OH)₂(H₂O)₂]·DMA·CH₃OH(1,1,4-H₂NDC=1,4-萘二酸,DMA=N,N'-二甲基乙酰胺),并对其结构表征及荧光性能进行了研究。 单晶X射线研究结果表明,化合物结晶于P2₁/c空间群,其晶体学数据为a=2.06090(12) nm, b=2.21014(13) nm, c=1.50385(10) nm, β=111.399(3)°, V=6.3776(7) nm³, Z=4, D_c=1.403 g/cm³, F(000)=2824, R=0.0596, wR=0.1225(I>2σ(I))。 化合物1中,二核的镁作为次级构筑单元通过桥连配体1,4-NDC连接形成沿c轴方向拓展的一维链。 一维链间进一步通过配体连接形成3D框架的化合物。 荧光性能研究表明,化合物1对CS₂具有灵敏的荧光传感性能,在0.4%的体积分数条件下可引起CS₂荧光的完全淬灭。 此外,化合物1的热稳定性也通过热重分析进行了研究,发现其可稳定到140 ℃左右。     

席夫碱型环磷腈类化合物的合成及光谱性质

通过亲核取代反应, 在2,2'-联苯二酚氧基环氯磷腈母体N₃P₃(O₂C₁₂H₈)₂Cl₂ (1)和N₃P₃(O₂C₁₂H₈)Cl₄ (2)上引入2-醛基吡啶与对胺基苯酚形成的席夫碱侧基, 合成了两种新型环磷腈化合物N₃P₃(O₂C₁₂H₈)₂(p-O-Ph-N＝C-Py)₂ (3)和N₃P₃(O₂C₁₂H₈)(p-O-Ph-N＝C-Py)₄ (4), 这些化合物是一类能形成配合物的多齿配体. 通过元素分析, IR, ¹H NMR, ³¹P NMR和TOFMS确定其结构, 研究了它们的吸收光谱和荧光光谱. H^＋和Cu^＋离子对其光谱性质的影响研究表明两种化合物的吸收和荧光光谱对H^＋和Cu^＋离子异常敏感, 因而在作为这些阳离子的荧光探针方面具有应用前景.     

樟脑酸衍生物构筑的单一手性金属有机骨架化合物的合成、表征及荧光性质

设计合成了一个新的手性樟脑酸衍生物[D-H₂ctba, H₂ctba=4-(3-羧基-2,2,3-三甲基环戊烷酰胺)苯甲酸]. 将其作为配体与硝酸镉通过溶剂热反应得到了新的手性金属有机骨架化合物[Cd₃(ctba)₃·H₂O]_n(1). 通过单晶X射线衍射(XRD)、 粉末X射线衍射(PXRD)、 元素分析、 热重分析(TGA)和圆二色(CD)光谱对该化合物进行了表征. 单晶结构解析表明, 该化合物具有单一手性结构, 以1个六核的Cd羧基簇为基本单元, 簇与簇之间通过羧基相连形成(-Cd-O-C-)_∞棒状次级结构单元, 次级结构单元之间由配体相连, 拓展成为三维的骨架结构. 荧光光谱测试结果表明, 该化合物在室温下具有较强的荧光性质.     

混合配体构筑的Zn(Ⅱ)金属有机骨架化合物的合成、 结构与荧光性质

在水热条件下, 利用锌离子与2种有机配体合成出1个结构新颖的金属有机骨架化合物[Zn₂(BPDC)(IN)₂](H₂BPDC=4,4'-联苯二羧酸; HIN=异烟酸), 并通过单晶X射线衍射、 红外光谱、 热重分析和荧光光谱等对该化合物进行了表征. 结果表明, 该化合物结构中Zn离子与BPDC的羧基形成双核金属次级结构单元[Zn₂(—CO₂)₂(IN)₂], 相邻次级结构单元通过IN配离子连接形成[Zn₂(—CO₂)₂(IN)₂]_∞二维层面, 相邻的二维层通过BPDC相互连接形成具有三重互穿的简单格子拓扑结构. 该化合物表现出良好的荧光性质.     

含有酯基及酰胺基柔链的苯并菲盘状液晶的合成、分子间氢键对柱状介晶性的影响

合成了三个系列, 共二十四个有两种不同软链的对称和非对称苯并菲盘状液晶化合物, C₁₈H₆(OR)₃- (OCH₂COOEt)₃, C₁₈H₆(OR)₃(OCH₂COOBu)₃, C₁₈H₆(OR)₃(OCH₂CONHBu)₃, 其中R＝C₅H₁₁, C₆H₁₃, C₇H₁₅, C₈H₁₇. 化合物通过柱层析纯化, 结构通过¹H NMR, IR, 元素分析等确证. 化合物热稳定性通过TGA测定, 并显示出较高的热稳定性. 通过偏光显微镜和差视扫描量热法对这些化合物的热致液晶性进行了研究. 结果显示: 对于苯并菲液晶化合物C₁₈H₆(OR)₃(OCH₂COOEt)₃, 非对称性化合物较之对称异构体化合物有更低的熔点和更高的清亮点, 因而非对称性化合物有更宽的介晶温度范围. 对于分子中含有酰胺基的苯并菲液晶化合物C₁₈H₆(OR)₃(OCH₂CONHBu)₃, 对称化合物有比非对称异构体更高的清亮点和更有序的六方柱状介晶相, 且其与具有同样软链长度的分子中不含酰胺基的化合物系列C₁₈H₆(OR)₃(OCH₂COOBu)₃相比较, 由于柱内分子间氢键的形成, 不仅有更高的熔点和清亮点, 而且有更丰富的柱状介晶相.     

9,9-二(十六烷基)芴基二聚炔铂、金和汞配合物的合成与性质

用Hagihara脱氢卤代法合成了三种新的9,9-二(十六烷基)芴基二聚炔铂(d⁸)、金和汞(d¹⁰)化合物反式- [Pt(Ph)(PEt₃)₂C≡CRC≡CPt(Ph)(PEt₃)₂, [(PPh₃)AuC≡CRC≡CAu(PPh₃)]和[MeHgC≡CRC≡CHgMe] [R＝9,9-二(十六烷基)芴基]. 用¹H NMR, ¹³C NMR, ³¹P NMR, FT-IR, FAB-MS, UV-Vis, 荧光和磷光光谱对其进行了表征. 结果表明, 体系中的铂、金和汞产生的重原子效应可以有效地促进单线激发态S₁与三线激发态T₁的系间跃迁, 使标题化合物产生有机三线态发光.     

一种具有荧光性质的阳离子Ga⁃MOF用于Fe3+和硝基化合物识别

通过溶剂热法合成了一种新型阳离子镓金属-有机框架Ga-MOF, 其化学式为[Ga₃O(H₂O)₃(TCA)₂]·NO₃·6DMF·2H₂O(JOU-27, H₃TCA=4,4′,4″-三苯胺三羧酸). 结构分析表明, JOU-27是基于氧心三核镓簇的三维微孔结构. 由于荧光配体H₃TCA的引入, JOU-27具有强的荧光发射强度, 因此可用于检测Fe³⁺离子和硝基芳香族化合物. 结果表明, 其对Fe³⁺的检出限低至2.22×10^-6 mol/L(Stern-Volmer常数K_SV=52823 L/mol); 当硝基苯(NB)浓度仅为3.27×10^-3 mol/L时, 荧光猝灭效率可达91%. 进一步的研究表明, JOU-27的猝灭性能可能与荧光共振能量转移(FRET)效应、 激发光吸收竞争以及骨架激发态与硝基芳烃化合物之间的电子转移有关.     

改性SiO2载体对邻菲咯啉钌荧光特性及氧敏感荧光膜性能的影响

为提高极性荧光指示剂Ru(dpp)₃Cl₂在非极性硅橡胶中的分散性,以沉淀白炭黑、气相白炭黑和甲基MQ树脂,载负荧光指示剂Ru(dpp)₃Cl₂,再填充到二甲基硅橡胶(PDMS)中,制备氧敏感荧光膜.以分光光度计和荧光光谱仪,研究载体种类对Ru(dpp)₃Cl₂的吸附性、荧光特性及氧敏感荧光膜性能的影响.白炭黑载负Ru(dpp)₃Cl₂的荧光发射光谱相对其稀溶液约红移20 nm.载体表面的甲基可减弱SiO₂载体对Ru(dpp)₃Cl₂分子的吸附性和相互作用,减少荧光发射光谱的红移12 nm,提高荧光强度近10倍.白炭黑有助改善Ru(dpp)₃Cl₂在PDMS中的分散性和氧敏感荧光膜的荧光输出和猝灭比,尤以MQ树脂的效果最为显著.     

八面体纳米笼构筑的金属-有机框架化合物

利用半刚性的三足羧酸配体1,3,5-tris[3-(carboxyphenyl)oxamethyl]-2,4,6-trimethylbenzene acid (H₃TBTC)与金属离子自组装成功合成了两例八面体纳米笼构建的金属-有机框架化合物: {[Zn₃TBTC₂(DMA)(H₂O)]·3DMA·3H₂O}_n (1), {[Cd₃TBTC₂(DMA)₂(H₂O)₂]·2DMA·2H₂O}_n (2). TBTC^3-配体在化合物中呈现出cis,cis,cis-和cis,trans,trans-两种构型. cis,cis,cis-构型的TBTC^3-配体与Zn₃(COO)₆次级结构基元(secondary building units, SBUs)构筑了畸变的八面体金属-有机纳米笼, 因而化合物的结构可以看成是八面体金属-有机纳米笼作为超分子构建单元(supramolecular building blocks, SBBs), 在空间上与cis,trans,trans-构型的配体相连, 最终形成具有(3,18)-连接的三维无限网络. 荧光测试结果表明, 化合物1～2的荧光都是基于配体的发射. 相对于配体的发射光谱, 化合物1～2的发射光谱展现出蓝移的现象. 气体吸附测试结果表明, 化合物1～2具有选择性吸附二氧化碳的能力.     

以5-(6-羧酸-2-萘基)-间苯二羧酸为配体构筑的两个镉的金属-有机骨架化合物的合成、晶体结构及荧光性质

在溶剂热条件下,以不对称三羧酸5-（6-羧酸-2-萘基）-间苯二羧酸（H3L）为配体合成了2个镉的金属-有机骨架化合物:{[Cd₃L₂（H₂O）₃]·6DMF}_n（1）和{[Cd₃L₂（H₂O）₄]·3DMA}_n（2）。通过X射线单晶衍射,粉末衍射,热重和红外光谱进行了结构表征。结构分析表明,1和2形成3,6-连接的三维结构,其拓扑符号分别为:（4⁵.6⁴.8⁶）（4³）₂和(6¹².8³)（6³）₂。此外,还对2个化合物进行了荧光分析。     

Electronic structure and properties of isoreticular metal-organic frameworks: the case of M-IRMOF1 (M = Zn, Cd, Be, Mg, and Ca)

We investigate the possibility of tailoring the electronic properties of isoreticular metal-organic materials by replacing the metal atom in the metal-organic cluster and by doping. The electronic structure of M-IRMOF1, where IRMOF1 stands for isoreticular metal-organic framework 1 and M = Be, Mg, Ca, Zn, and Cd, was examined using density-functional theory. The results show that these materials have similar band gaps (ca. 3.5 eV) and a conduction band that is split into two bands, the lower of which has a width that varies with metal substitution. This variation prompted us to investigate whether doping with Al or Li could be used to tailor the electronic properties of the Zn-IRMOF1 and Be-IRMOF1 materials. It is shown that replacing one metal atom with Al can effectively be used to create IRMOFs with different metallic properties. On the other hand, adding Li produces structural changes that render this approach less suitable.     

Room temperature synthesis of metal-organic frameworks: MOF-5, MOF-74, MOF-177, MOF-199, and IRMOF-0

Room temperature synthesis of metal-organic frameworks (MOFs) has been developed for four well-known MOFs: MOF-5, MOF-74, MOF-177, and MOF-199. A new isoreticular metal framework (IRMOF), IRMOF-0, having the same cubic topology as MOF-5, has been synthesized from acetylenedicarboxylic acid using this method to accommodate the thermal sensitivity of the linker. Despite acetylenedicarboxylate being the shortest straight linker that can be made into an IRMOF, IRMOF-0 forms as a doubly interpenetrating structure, owing to the rod-like nature of the linker.     

Tandem postsynthetic modification of metal-organic frameworks using an inverse-electron-demand Diels-Alder reaction

A postsynthetic modification (PSM) scheme for metal-organic frameworks (MOFs) has been developed using a tetrazine-based "Click" reaction. It was found that the efficacy of this modification procedure was dependent on the MOF topology and, in the case of an isoreticular MOF (IRMOF) system, required the formation of a mixed-ligand IRMOF with a suitable ratio of 1,4-benzenedicarboxylate (BDC) and an olefin-tagged BDC derivative. On the basis of the versatile use of tetrazine "Click" chemistry in bioconjugate chemistry, we expect that this scheme will prove to be a useful reaction for preparing functionalized materials, including MOFs.     

Systematic functionalization of a metal-organic framework via a postsynthetic modification approach

The pendant amino groups in isoreticular metal-organic framework-3 (IRMOF-3) were subjected to postsynthetic modification with 10 linear alkyl anhydrides (O(CO(CH2)nCH3)2 (where n = 1 to 18) and the extent of conversion, thermal and structural stability, and Brunauer-Emmett-Teller (BET) surface areas of the resulting materials were probed. (1)H NMR of digested samples showed that longer alkyl chain anhydrides resulted in lower conversions of IRMOF-3 to the corresponding amide framework (designated as IRMOF-3-AM2 to IRMOF-3-AM19). Percent conversions ranged from essentially quantitative (approximately 99%, -AM2) to approximately 7% (-AM19) with IRMOF-3 samples. Modified samples were thermally stable up to approximately 430 degrees C and remained crystalline based on powder X-ray diffraction (PXRD) measurements. Under specific reaction conditions, significant conversions were obtained with complete retention of crystallinity, as verified by single-crystal X-ray diffraction experiments. Single crystals of modified IRMOF-3 samples all showed that the F-centered cubic framework was preserved. All single crystals used for X-ray diffraction were analyzed by electrospray ionization mass spectrometry (ESI-MS) to confirm that these frameworks contained the modified 1,4-benzenedicarboxylate ligand. Single crystals of each modified IRMOF-3 were further characterized by measuring the dinitrogen gas sorption of each framework to determine the effects of modification on the porosity of the MOF. BET surface areas (m(2)/g) confirmed that all modified IRMOF-3 samples maintained microporosity regardless of the extent of modification. The surface area of modified MOFs was found to correlate to the size and number of substituents added to the framework.     

Tuning Hydrogen Sorption Properties of Metal–Organic Frameworks by Postsynthetic Covalent Modification

Postsynthetic modification is presented as a means to tune the hydrogen adsorption properties of a series of metal–organic frameworks (MOFs). IRMOF‐3 (isoreticular metal–organic framework), UMCM‐1‐NH₂ (University of Michigan crystalline material), and DMOF‐1‐NH₂ (DABCO metal–organic framework) have been covalently modified with a series of anhydrides or isocyanates and the hydrogen sorption properties have been studied. Both the storage capacities and isosteric heats of adsorption clearly show that covalent postsynthetic modification can significantly enhance the sorption affinity of MOFs with hydrogen and in some cases increase both gravimetric and volumetric uptake of the gas as much as 40 %. The significance of the present study is illustrated by: 1) the nature of the substituents introduced by postsynthetic modification result in different effects on the binding of hydrogen; 2) the covalent postsynthetic modification approach allows for systematic modulation of hydrogen sorption properties; and 3) the ease of postsynthetic modification of MOFs allows a direct evaluation of the interplay between MOF structure, hydrogen uptake, and heat of adsorption. The findings presented herein show that postsynthetic modification is a powerful method to manipulate and better understand the gas sorption properties of MOFs.     

Binding energies of hydrogen molecules to isoreticular metal-organic framework materials

Recently, several novel isoreticular metal-organic framework (IRMOF) structures have been fabricated and tested for hydrogen storage applications. To improve our understanding of these materials, and to promote quantitative calculations and simulations, the binding energies of hydrogen molecules to the MOF have been studied. High-quality second-order Moller-Plesset (MP2) calculations using the resolution of the identity approximation and the quadruple zeta QZVPP basis set were used. These calculations use terminated molecular fragments from the MOF materials. For H2 on the zinc oxide corners, the MP2 binding energy using Zn4O(HCO2)6 molecule is 6.28 kJ/mol. For H2 on the linkers, the binding energy is calculated using lithium-terminated molecular fragments. The MP2 results with coupled-cluster singles and doubles and noniterative triples method corrections and charge-transfer corrections are 4.16 kJ/mol for IRMOF-1, 4.72 kJ/mol for IRMOF-3, 4.86 kJ/mol for IRMOF-6, 4.54 kJ/mol for IRMOF-8, 5.50 and 4.90 kJ/mol for IRMOF-12, 4.87 and 4.84 kJ/mol for IRMOF-14, 5.42 kJ/mol for IRMOF-18, and 4.97 and 4.66 kJ/mol for IRMOF-993. The larger linkers are all able to bind multiple hydrogen molecules per side. The linkers of IRMOF-12, IRMOF-993, and IRMOF-14 can bind two to three, three, and four hydrogen molecules per side, respectively. In general, the larger linkers have the largest binding energies, and, together with the enhanced surface area available for binding, will provide increased hydrogen storage. We also find that adding up NH2 or CH3 groups to each linker can provide up to a 33% increase in the binding energy.     

Properties of IRMOF-14 and its analogues M-IRMOF-14 (M = Cd, alkaline earth metals): electronic structure, structural stability, chemical bonding, and optical properties

The chemical bonding, electronic structure, and optical properties of the experimentally available metal-organic framework IRMOF-14 and its metal-substituted analogues M-IRMOF-14 (M = Zn, Cd, Be, Mg, Ca, Sr, Ba), which contain a pyrene-2,7-dicarboxylate linker group, have been systematically investigated using DFT calculations. The unit cell volume and atomic positions were optimized with the Perdew-Burke-Ernzerhof (PBE) functional and showed good agreement between experimental and theoretical equilibrium structural parameters for Zn-IRMOF-14. The calculated bulk moduli indicate that the whole M-IRMOF-14 series are soft materials. The estimated band gap from DOS calculations for the M-IRMOF-14 series is ca. 2.5 eV, essentially independent of the metal ion and indicative of nonmetallic character. The band gap value is distinctly different from those calculated previously for the M-IRMOF-1 (benzene-1,4-dicarboxylate linker; ca. 3.5 eV) and M-IRMOF-10 (biphenyl-4,4'-dicarboxylate linker; ca. 3.0 eV) series and this confirms that the identity of the linker is a key parameter to control band gaps in an isoreticular series of main-group MOFs. In view of potential uses of MOFs in organic semiconducting devices such as field-effect transistors, solar cells, and organic light-emitting devices, the linear optical properties of these materials were also investigated. Comparisons are made with the M-IRMOF-1 and M-IRMOF-10 series.     

Two-dimensional metal-organic frameworks (MOFs) constructed from heterotrinuclear coordination units and 4,4'-biphenyldicarboxylate ligands

Three novel metal-organic frameworks (MOFs) formulated as [Zn(2)M(BPDC)(3)(DMF)(2)].4DMF (M = Co(II), Ni(II) or Cd(II); BPDC = 4,4'-biphenyldicarboxylate; DMF = N,N'-dimethylformamide) have been prepared via solvothermal synthesis from mixtures of the corresponding transition metal salts and 4,4'-biphenyldicarboxylic acid (H(2)BPDC). The framework structures are characterized by single-crystal X-ray diffraction analysis, IR and UV-vis diffuse reflectance spectroscopy, thermogravimetric analysis (TGA), and X-ray powder diffraction (XRPD). All three compounds possess essentially the same 2-D layered coordination framework consisting of linear heterotrinuclear secondary building units (SBUs) connected by rigid bridging BPDC ligands. Crystal data: for (C(60)H(66)CoN(6)O(18)Zn(2)): monoclinic, space group P2(1)/n, M = 1348.86, a = 20.463(4), b = 14.819(3), c = 23.023(5) A, beta = 111.75(3) degrees , V = 6484(2) A(3), Z = 4, D(c) = 1.382 Mg m(-3). For (C(60)H(66)N(6)NiO(18)Zn(2)): monoclinic, space group P2(1)/n, M = 1348.64, a = 11.670(2), b = 14.742(3), c = 19.391(4) A, beta = 102.29(3) degrees , V = 3259.5(11) A(3), Z = 2, D(c) = 1.374 Mg m(-3). For (C(60)H(66)CdN(6)O(18)Zn(2)): monoclinic, space group P2(1)/n, M = 1402.33, a = 11.491(2), b = 14.837(3), c = 19.386(4) A, beta = 101.53(3) degrees , V = 3238.3(11) A(3), Z = 2, D(c) = 1.438 Mg m(-3).     

New isoreticular metal-organic framework materials for high hydrogen storage capacity

We propose new isoreticular metal-organic framework (IRMOF) materials to increase the hydrogen storage capacity at room temperature. Based on the potential-energy surface of hydrogen molecules on IRMOF linkers and the interaction energy between hydrogen molecules, we estimate the saturation value of hydrogen sorption capacity at room temperature. We discuss design criteria and propose new IRMOF materials that have high gravimetric and volumetric hydrogen storage densities. These new IRMOF materials may have gravimetric storage density up to 6.5 wt % and volumetric storage density up to 40 kg H2/m3 at room temperature.     

Alkali‐Metal Azides Interacting with Metal–Organic Frameworks

Interactions between alkali‐metal azides and metal–organic framework (MOF) derivatives, namely, the first and third members of the isoreticular MOF (IRMOF) family, IRMOF‐1 and IRMOF‐3, are studied within the density functional theory (DFT) paradigm. The investigations take into account different models of the selected IRMOFs. The mutual influence between the alkali‐metal azides and the π rings or Zn centers of the involved MOF derivatives are studied by considering the interactions both of the alkali‐metal cations with model aromatic centers and of the alkali‐metal azides with distinct sites of differently sized models of IRMOF‐1 and IRMOF‐3. Several exchange and correlation functionals are employed to calculate the corresponding interaction energies. Remarkably, it is found that, with increasing alkali‐metal atom size, the latter decrease for cations interacting with the π‐ring systems and increase for the azides interacting with the MOF fragments. The opposite behavior is explained by stabilization effects on the azide moieties and determined by the Zn atoms, which constitute the inorganic vertices of the IRMOF species. Larger cations can, in fact, coordinate more efficiently to both the aromatic center and the azide anion, and thus stabilizing bridging arrangements of the azide between one alkali‐metal and two Zn atoms in an η² coordination mode are more favored.