Molecular tectonics on surfaces: Bottom-up fabrication of 1D coordination networks that form 1D and 2D arrays on graphite.
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Crystallography, X-Ray↗
Biomedical subjects
Mir Wais Hosseini
Publications and source records attributed to Mir Wais Hosseini.
Arranging up to six ferrocene carboxamides around metal centres.
Ferrocene carboxamide, FcCONH(2), forms homo- and heteroleptic complexes with Co(II), Ni(II) and Cu(II) via coordination of its carbonyl group. Whereas for both Co(II) and Ni(II), hexaferrocenyl complexes are obtained in the presence of BF(4)(-) anion, in the case of Cu(II) a tetraferrocenyl species is observed in the presence of triflate anion.
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Sequential generation of one-dimensional networks based on a differentiated bischelate-type ligand bearing both 4,5-diazafluorene and dithiolene units.
A novel dithiolene ligand appended with a 4,5-diazafluorene moiety has been synthesized and used for the preparation of discrete nickel and mercury complexes and a one-dimensional polymer in the presence of sodium cations.
Aza Compounds↗
Orthogonal packing of enantiomerically pure helical silver coordination networks.
The combination of the chiral tecton based on the (R)-6,6'-dibromo-1,1'-binaphthyl moiety bearing two isonicotinoyl groups with AgX (X = BF4-, CF3SO3-, PF6-) leads to the formation of enantiomerically pure helical strands with orthogonal packing in the rare space group I2(1)3.
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Self-assembly and generation of complexity.
Supramolecular synthesis, by combining molecules through non-covalent interactions, makes it possible to build up extremely sophisticated supramolecular assemblies in the solid state and offers endless architectural possibilities.
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Reversible single-crystal-to-single-crystal guest exchange in a 3-D coordination network based on a zinc porphyrin.
A self-complementary tecton based on a zinc porphyrin core bearing two pyridines at the opposite meso positions leads to the formation of a 3-D coordination network in the crystalline phase which offers channels which are filled with solvent molecules; reversible exchange of the guest molecules has been proven to take place in a single-crystal-to-single-crystal type transformation demonstrating the robustness of the coordination framework.
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Alkoxo-bridged copperII complexes as nodes in designing solid-state architectures. The interplay of coordinative and d10-d10 metal-metal interactions in sustaining supramolecular solid-state architectures.
Four novel polymeric coordination networks have been obtained through self-assembly processes involving alkoxo-bridged copperII species as nodes, and anionic cyano-complexes as linkers: infinity2[{Cu2(pa)2}{M(CN)2}2](M=Ag, 1; Au, 2), (infinity)3[{Cu4(mea)4}{Au(CN)2}4.H2O]3, and (infinity)3[{Cu2(pa)2}{Ni(CN)4}](pa = deprotonated propanolamine; mea = deprotonated monoethanolamine). The supramolecular architectures of compounds 1, and 2 are sustained by argentophilic or strong aurophilic interactions. The solid-state architectures of 1 and 2, which are isomorphous, consist of infinite layers, constructed from binuclear alkoxo-bridged nodes and [M(CN)2]- spacers. The layers are stacked in an offset parallel mode, and are further interconnected through Ag...Ag or Au...Au contacts (1: Ag...Ag 3.015 A; 2: Au....Au 3.069 A). Compound 3 consists of unique fourfold interpenetrating diamondoid nets. The diamondoid topology is built of heterocubane {Cu4O4} nodes, which are connected by [Au(CN)2]- rods. The Cu-O distances within the {Cu4O4} node vary between 1.927(2) and 2.679(1) A, showing unsymmetric bridging of the copper atoms. Aurophilic interactions are established between the bridging and terminal [Au(CN)2]- metalloligands, and connect the interpenetrating nets, resulting in infinite chains of gold atoms (the Au...Au distances vary between 3.253 and 3.305 [Angstrom]). Compound 4 exhibits a 3-D network constructed from {Cu2(pa)2]2+ nodes connected by square-planar [Ni(CN)4]2- ions. Compounds 1, 2 and 4 are weakly paramagnetic. The cryomagnetic investigation of reveals a gradual increase, followed by a decrease of the chiMT product, as the temperature is lowered. A superposition of ferro- (J1=+20.8 cm(-1)) and antiferromagnetic (J2=-6.4) interactions within the tetranuclear node was found. Antiferromagnetic interactions are established between the tetranuclear nodes (theta=-2.99 K).
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Molecular tectonics: from simple tectons to complex molecular networks.
Molecular networks in the crystalline phase are infinite periodic molecular assemblies formed under self-assembly conditions between self-complementary or complementary tectons. These millimeter-size structures may be regarded as hypermolecules formed by supramolecular synthesis using reversible intertecton interactions. Molecular tectonics, based on molecular recognition events and their iteration, is the approach dealing with design and preparation of molecular networks in the solid state. In this Account, an overview of the rational behind this approach is presented. A variety of molecular networks based on van der Waals interactions and hydrogen and coordination bonding possessing diverse connectivity and topology are discussed.
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Molecular tectonics: design of luminescent H-bonded molecular networks.
Using bis-amidinium dications as tetra H-bond donor tectons and Au(CN)(2)(-) anion, neutral 1-D networks based on a bis monohapto mode of H-bonding are obtained. Owing to the short metal-metal distance within the network, luminescent crystals are obtained. The emission phenomena may be tuned by the nature of the spacer connecting the two cyclic amidinium groups.
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Molecular tectonics: from enantiomerically pure sugars to enantiomerically pure triple stranded helical coordination network.
The self-assembly between a bis-monodentate tecton based on two pyridine units connected to an enantiomerically pure isomannide stereoisomer and HgCl2 leads to the formation of an enantiomerically pure triple stranded helical infinite coordination network which was structurally characterised by X-ray diffraction on single crystal.
Binding Sites↗
Charge assisted chiral hybrid H-bonded molecular networks.
The co-crystallisation of [Fe(CN)5NO]2- and cyclic achiral 1(2+) and chiral 2(2+) or 3(2+) bisamidinium tectons leads in the crystalline phase to the formation of 1-D H-bonded achiral and chiral molecular networks respectively. In all cases, the network is formed by mutual bridging of the anionic and cationic units through a chelate mode of H-bonding.
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Molecular tectonics: infinite cationic double stranded helical coordination networks.
Upon crystallisation of two bismonodentate tectons based on two pyridine units, interconnected at the meta position by a tetra- or hexa-ethylene glycol fragment and Ag+ cation, double stranded helical infinite coordination networks were formed and structurally characterised. The cationic double helical architectures obtained may be regarded as analogues of DNA in terms of topology.
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Non-centrosymmetric packing of 1-D coordination networks based on chirality.
Using CoCl2 and a chiral tecton possessing C2 chirality and based on two coordination poles composed of a pyridine unit connected at the 4-position to a pyridine bearing at the 2 and 6 positions two optically active oxazoline moieties, a polar solid is obtained. The latter results from the acentric packing of directional 1-D coordination networks.
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Koilands from thiophiles: mercury(II) clusters from thiacalixarenes.
Tetra- and hexa-nuclear mercury(II) complexes have been obtained from tetrathiacalix[4]arene and tetramercaptotetrathiacalix[4]arene, respectively, and structurally characterised in the solid state; the complexes provide new digonal and trigonal receptors of the koiland type.
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Second sphere supramolecular chirality: racemic hybrid H-bonded 2-D molecular networks.
Neutral hybrid 2-D networks have been generated using a bis-amidinium capable of chelating M(CN)6(3-) anions via hydrogen bonds: the packing of the achiral 2-D networks leads to channels which are occupied by water molecules forming polymeric H-bonded chains; furthermore, owing to the dihapto mode of H-bonding, the presence of supramolecular chirality of the delta' and lambda' types taking place within the second coordination sphere of the metallic centre has been demonstrated.
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Design of 3-D coordination networks: topology and metrics.
Using 4,4',4"-tricyanotriphenylmethanol 1 as a heterotetradentate tecton with C3v symmetry bearing three CN and one OH group, under self-assembly conditions a 3-D coordination network was obtained in the presence of Ag+ cations acting as a tetrahedral metallic tecton; due to the metrics of 1 (three long and one short distance between the central C atom and N and O coordination sites, respectively), the 3-D network is of pseudo-diamondoid type with different cavity sizes; although a two-fold homo-interpenetration is observed for the 3-D networks, the remaining space is occupied by CHCl3, MeOH solvent molecules and SbF6- anions.
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