Kinetic trapping of 2,4,6-tris(4-pyridyl)benzene and ZnI2 into M12L8 poly-[n]-catenanes using solution and solid-state processes

: Here, we show that in a supramolecular system with more than 20 building blocks forming large icosahedral M12L8 metal-organic cages (MOCs), using the instant synthesis method, it is possible to kinetically trap and control the formation of interlocking M12L8 nanocages, giving rare M12L8 TPB-ZnI2 poly-[n]-catenane. The catenanes are obtained in a one-pot reaction, selectively as amorphous (a1) or crystalline states, as demonstrated by powder X-ray diffraction (powder XRD), thermogravimetric (TG) analysis and 1H NMR. The 300 K M12L8 poly-[n]-catenane single crystal X-ray diffraction (SC-XRD) structure including nitrobenzene (1) indicates strong guest binding with the large M12L8 cage (i.e., internal volume ca. 2600 Å3), allowing its structural resolution. Conversely, slow self-assembly (5 days) leads to a mixture of the M12L8 poly-[n]-catenane and a new TPB-ZnI2 (2) coordination polymer (i.e., thermodynamic product), as revealed by SC-XRD. The neat grinding solid-state synthesis also yields amorphous M12L8 poly-[n]-catenane (a1'), but not coordination polymers, selectively in 15 min. The dynamic behavior of the M12L8 poly-[n]-catenanes demonstrated by the amorphous-to-crystalline transformation upon the uptake of ortho-, meta- and para-xylenes shows the potential of M12L8 poly-[n]-catenanes as functional materials in molecular separation. Finally, combining SC-XRD of 1 and DFT calculations specific for the solid-state, the role of the guests in the stability of the 1D chains of M12L8 nanocages is reported. Energy interactions such as interaction energies (E), lattice energies (E*), host-guest energies (Ehost-guest) and guest-guest energies (Eguest-guest) were analysed considering the X-ray structure with and without the nitrobenzene guest. Not only the synthetic control achieved in the synthesis of the M12L8 MOCs but also their dynamic behavior either in the crystalline or amorphous phase are sufficient to raise scientific interest in areas ranging from fundamental to applied sides of chemistry and material sciences

Insights into the formation of chiral second sphere coordination complexes with aromatic tris amines: combined single crystal X-ray crystallography and molecular modeling analyses

Insights into the formation of chiral second sphere coordination complexes with aromatic tris amines: combined single crystal X-ray crystallography and molecular modeling analyses Antonino Famulari, Massimo Cametti and Stefano Valdo Meille (Politecnico di Milano), and Javier Martí-Rujas (Center for Nano Science and Technology@Polimi, Istituto Italiano di Tecnologia) Control over the formation of non-centrosymmetric chiral materials is highly desirable due to their potential applications in areas such as ferroelectricity, piezo- and pyroelectricity, and second harmonic generation.[1] The development of a reliable approach to induce the formation of a chiral material from achiral molecules remains a great challenge in the field of molecular chemistry.[2] Furthermore, the understanding of the driving forces behind those aggregations is a prerequisite for the design and construction of chiral molecular arrays. C3-symmetrical tripodal molecules have emerged as attractive organic frameworks for the construction of chiral coordination compounds.[3] In the present contribution we report about a family of isostructural, chiral supramolecular networks obtained in the solid state by exploiting second sphere coordination interactions in the self-assembly of 2 achiral tris amines with tetrahalometallate and halide ions. Quantum-Mechanical calculations (including the usage of approaches specific for crystalline solid phases) provided important insights into the intramolecular and packing interactions which determine chirality, pointing to a direct effect of the methyl groups of the central benzene ring of the tris amines. [4] [1] (a) P. A. Maggard, C. L. Stern and K. R. Poeppelmeier, J. Am. Chem. Soc., 2001, 123, 7742–7743; (b) M. Liu, L. Zhang and T. Wang, Chem. Rev., 2015, DOI: 10.1021/ Q5 cr500671p. [2] P. S. Halasyamani and K. R. Poeppelmeyer, Chem. Mater., 1998, 10, 2753–2769. [3] Z. Dai and J. W. Canary, New J. Chem., 2007, 31, 1708–1718. [4] H. Yu, L. Li, J. Gao, J. Tong, W. Zheng, M. Cametti, A. Famulari, S.V. Meille, F. Guo and J. Martí-Rujas Journal Article Dalton Trans., 2016,44, 15960-15965. DOI: 10.1039/C5DT02387D

Exploiting polymorphism in second sphere coordination: thermal transformation, NLO properties and selective mechanochemical synthesis

The racemic organic building block L acting as a first sphere ligand yields a new second sphere adduct [LH]+·[FeCl4]- crystallizing as racemic polymorphs α and β. Solid-state DFT calculations show that polymorph β is the kinetic adduct as observed experimentally. The β-phase crystallizes in the polar space group Pna21 and displays NLO properties. Mechanochemical synthesis yields only the β-phase

Thermal Reactivity in Metal Organic Materials (MOMs): From Single-Crystal-to-Single-Crystal Reactions and Beyond

Thermal treatment is important in the solid-state chemistry of metal organic materials (MOMs) because it can create unexpected new structures with unique properties and applications that otherwise in the solution state are very difficult or impossible to achieve. Additionally, high-temperature solid-state reactivity provide insights to better understand chemical processes taking place in the solid-state. This review article describes relevant thermally induced solid-state reactions in metal organic materials, which include metal organic frameworks (MOFs)/coordination polymers (CPs), and second coordination sphere adducts (SSCs). High temperature solid-state reactivity can occur in a single-crystal-to-single crystal manner (SCSC) usually for cases where there is small atomic motion, allowing full structural characterization by single crystal X-ray diffraction (SC-XRD) analysis. However, for the cases in which the structural transformations are severe, often the crystallinity of the metal-organic material is damaged, and this happens in a crystal-to-polycrystalline manner. For such cases, in the absence of suitable single crystals, structural characterization has to be carried out using ab initio powder X-ray diffraction analysis or pair distribution function (PDF) analysis when the product is amorphous. In this article, relevant thermally induced SCSC reactions and crystal-to-polycrystalline reactions in MOMs that involve significant structural transformations as a result of the molecular/atomic motion are described. Thermal reactivity focusing on cleavage and formation of coordination and covalent bonds, crystalline-to-amorphous-to-crystalline transformations, host–guest behavior and dehydrochlorination reactions in MOFs and SSCs will be discussed

Selective adsorption of chlorinated volatile organic compound vapours by microcrystalline 1D coordination polymers

Microcrystalline 1D coordination polymers 1-3Pwd are able to adsorb vapours of chlorinated volatile organic compounds (Cl-VOCs), displaying interesting selectivity patterns, as demonstrated by 1H-NMR and X-ray diffraction analyses. Due to their dynamic breathing-like behavior, chemical and thermal stabilities and adsorption selectivity, these isostructural coordination polymers are promising to be used as filters for toxic Cl-VOCs

Structural memory effect in solid-state transformation of kinetic coordination networks

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Structure Determination of Host-Guest Networks: Short Contacts between TTF Molecules in a Pore

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