Synthesis and solid-state characterisation of 4-substituted methylidene oxindoles

Background 4-substituted methylidene oxindoles are pharmacologically important. Detailed analysis and comparison of all the interactions present in crystal structures is necessary to understand how these structures arise. The XPac procedure allows comparison of complete crystal structures of related families of compounds to identify assemblies that are mainly the result of close-packing as well as networks of directed interactions. Results Five 4-substituted methylidene oxindoles have been synthesized by the Knoevenagel condensation of oxindole with para-substituted aromatic aldehydes and were characterized in the solid state by x-ray crystallography. Hence, the structures of (3E)-3-(4-Bromobenzylidene)-1,3-dihydro-2H-indol-2-one, 3a, (3E)-3-(4-Chlorobenzylidene)-1,3-dihydro-2H-indol-2-one, 3b, (3E)-3-(4-Methoxybenzylidene)-1,3-dihydro-2H-indol-2-one, 3c, (3E)-3-(4-Methylbenzylidene)-1,3-dihydro-2H-indol-2-one, 3d and (3E)-3-(4-Nitrobenzylidene)-1,3-dihydro-2H-indol-2-one, 3e, were elucidated using single crystal X-ray crystallography. Conclusions A hydrogen bonded dimer molecular assembly or supramolecular construct was identified in all the crystal structures examined along with a further four 1D supramolecular constructs which were common to at least two of the family of structures studied. The 1D supramolecular constructs indicate that once the obvious strong interaction is satisfied to form hydrogen bonded dimer it is the conventionally weaker interactions, such as steric bulk and edge-to-face interactions which compete to influence the final structure formation

Synthesis of ‘unfeasible’ zeolites

R.E.M. thanks the Royal Society and the E.P.S.R.C. (Grants EP/L014475/1, EP/K025112/1 and EP/K005499/1) for funding work in this area. J.Č. and P.N. acknowledge the Czech Science Foundation for the project of the Centre of Excellence (P106/12/G015) and the European Union Seventh Framework Programme (FP7/ 2007-­‐2013) under grant agreement n°604307. The research leading to these results has received funding from the European Union Seventh Framework Programme under Grant Agreement 312483 – ESTEEM2 (Integrated Infrastructure Initiative–I3). We thank Professor Wuzong Zhou and Dr. Fengjiao Yu for their expertise in TEM and Daniel Dawson for help with NMR.Zeolites are porous aluminosilicate materials that have found applications in many different technologies. However, although simulations suggest that there are millions of possible zeolite topologies, only a little over 200 zeolite frameworks of all compositions are currently known, of which about 50 are pure silica materials. This is known as the zeolite conundrum - why have only so few of all the possible structures been made? Several criteria have been formulated to explain why most zeolites are unfeasible synthesis targets. Here we demonstrate the synthesis of two such 'unfeasible' zeolites, IPC-9 and IPC-10, through the assembly-disassembly-organization-reassembly mechanism. These new high-silica zeolites have rare characteristics, such as windows that comprise odd-membered rings. Their synthesis opens up the possibility of preparing other zeolites that have not been accessible by traditional solvothermal synthetic methods. We envisage that these findings may lead to a step change in the number and types of zeolites available for future applications.PostprintPeer reviewe

Magnetic and Photoluminescent Sensors Based on Metal-Organic Frameworks Built up from 2-aminoisonicotinate

Red Guipuzcoana de Ciencia, Tecnologia e Innovacion OF218/2018 University of Basque Country GIU 17/13 Basque Government IT1005-16 IT1291-19 IT1310-19 Junta de Andalucia FQM-394 Spanish Ministry of Science, Innovation and Universities (MCIU/AEI/FEDER, UE) PGC2018-102052-A-C22 PGC2018-102052-B-C21 MAT2016-75883-C2-1-P European Union (EU) ESFIn this work, three isostructural metal-organic frameworks based on frst row transition metal ions and 2-aminoisonicotinate (2ain) ligands, namely, {[M(μ-2ain)2]·DMF}n [MII=Co (1), Ni (2), Zn (3)], are evaluated for their sensing capacity of various solvents and metal ions by monitoring the modulation of their magnetic and photoluminescence properties. The crystal structure consists of an open diamond-like topological 3D framework that leaves huge voids, which allows crystallizing two-fold interpenetrated architecture that still retains large porosity. Magnetic measurements performed on 1 reveal the occurrence of feld-induced spin-glass behaviour characterized by a frequency-independent relaxation. Solvent-exchange experiments lead successfully to the replacement of lattice molecules by DMSO and MeOH, which, on its part, show dominating SIM behaviour with low blocking temperatures but substantially high energy barriers for the reversal of the magnetization. Photoluminescence studied at variable temperature on compound 3 show its capacity to provide bright blue emission under UV excitation, which proceeds through a ligand-centred charge transfer mechanism as confrmed by timedependent DFT calculations. Turn-of and/or shift of the emission is observed for suspensions of 3 in diferent solvents and aqueous solutions containing metal ions

A zeolite family with expanding structural complexity and embedded isoreticular structures

The authors acknowledge financial support from the Swedish Research Council (VR), the Swedish Governmental Agency for Innovation Systems (VINNOVA), the Röntgen-Ångström Cluster through the project grant MATsynCELL, the Knut and Alice Wallenberg Foundation through the project grant 3DEM-NATUR, the NCRI (2012R1A3A-2048833) and BK 21-plus programmes through the National Research Foundation of Korea, and the UK EPSRC (EP/J02077X/1).The prediction and synthesis of new crystal structures enable the targeted preparation of materials with desired properties. Among porous solids, this has been achieved for metal–organic frameworks1, 2, 3, but not for the more widely applicable zeolites4, 5, where new materials are usually discovered using exploratory synthesis. Although millions of hypothetical zeolite structures have been proposed6, 7, not enough is known about their synthesis mechanism to allow any given structure to be prepared. Here we present an approach that combines structure solution with structure prediction, and inspires the targeted synthesis of new super-complex zeolites. We used electron diffraction to identify a family of related structures and to discover the structural ‘coding’ within them. This allowed us to determine the complex, and previously unknown, structure of zeolite ZSM-25 (ref. 8), which has the largest unit-cell volume of all known zeolites (91,554 cubic ångströms) and demonstrates selective CO2 adsorption. By extending our method, we were able to predict other members of a family of increasingly complex, but structurally related, zeolites and to synthesize two more-complex zeolites in the family, PST-20 and PST-25, with much larger cell volumes (166,988 and 275,178 cubic ångströms, respectively) and similar selective adsorption properties. Members of this family have the same symmetry, but an expanding unit cell, and are related by hitherto unrecognized structural principles; we call these family members embedded isoreticular zeolite structures.PostprintPostprintPeer reviewe