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An emerging strategy for making ordered materials is modular construction, which connects preformed molecular subunits to neighbours through interactions of properly selected reactive sites. This strategy has yielded remarkable materials, including metal–organic frameworks joined by coordinative bonds, supramolecular networks linked by strong non-covalent interactions, and covalent organic frameworks in which atoms of carbon and other light elements are bonded covalently. However, the strategy has not yet produced covalently bonded organic materials in the form of large single crystals. Here we show that such materials can result from reversible self-addition polymerizations of suitably designed monomers. In particular, monomers with four tetrahedrally oriented nitroso groups polymerize to form diamondoid azodioxy networks that can be fully characterized by single-crystal X-ray diffraction. This work forges a strong new link between polymer science and supramolecular chemistry by showing how predictably ordered covalent or non-covalent structures can both be built using a single modular strategy. Modular construction using connectable molecular subunits is a powerful strategy for making new carbon-based materials. So far, large crystals have been produced only from subunits linked by weak interactions. Covalently bonded analogues have now been prepared by reversible self-addition polymerization of suitable monomers and structurally characterized by single-crystal X-ray diffraction.

An anthraquinone chromophore displaying a vivid violet color in solution was synthesized and it was thoroughly characterized both spectroscopically and electrochemically, along with its X-ray crystallography. Single crystal X-ray analysis of the chromophore revealed a nearly planar π-conjugated framework with short intermolecular contacts. Cyclic voltammetry revealed two consecutive one-electron reductions, corresponding to the formation of its radical anion and dianion. The spectroelectrochemistry of the chromophore confirmed two distinct and reversible color changes with the stepwise electrochemical reduction. These were quantified via the CIE L a* b* color space. Large optical differences (98%) between the bleached and colored states were observed along with a coloration efficiency of 698 cm2/C. These parameters confirm the anthraquinone is an ideal electrochrome: capable of reversibly switching its colors with applied potential. The three color changes and color bleaching associated with the neutral, radical anion, dianion, and cation, respectively, are also of interest for extending the palette of colors of molecular electrochromes toward panchromatic color tuning with molecular structure for use in smart windows and displays.

[PdCl4]2− dianions are oriented within a crystal in such a way that a Cl of one unit approaches the Pd of another from directly above. Quantum calculations find this interaction to be highly repulsive with a large positive interaction energy. The placement of neutral ligands in their vicinity reduces the repulsion, but the interaction remains highly endothermic. When the ligands acquire a unit positive charge, the electrostatic component and the full interaction energy become quite negative, signalling an exothermic association. Raising the charge on these counterions to +2 has little further stabilizing effect, and in fact reduces the electrostatic attraction. The ability of the counterions to promote the interaction is attributed in part to the H-bonds which they form with both dianions, acting as a sort of glue.

Perovskites with low ionic radii metal centres (for example, Ge perovskites) experience both geometrical constraints and a gain in electronic energy through distortion; for these reasons, synthetic attempts do not lead to octahedral [GeI 6 ] perovskites, but rather, these crystallize into polar non-perovskite structures 1 – 6 . Here, inspired by the principles of supramolecular synthons 7 , 8 , we report the assembly of an organic scaffold within perovskite structures with the goal of influencing the geometric arrangement and electronic configuration of the crystal, resulting in the suppression of the lone pair expression of Ge and templating the symmetric octahedra. We find that, to produce extended homomeric non-covalent bonding, the organic motif needs to possess self-complementary properties implemented using distinct donor and acceptor sites. Compared with the non-perovskite structure, the resulting [GeI 6 ] 4− octahedra exhibit a direct bandgap with significant redshift (more than 0.5 eV, measured experimentally), 10 times lower octahedral distortion (inferred from measured single-crystal X-ray diffraction data) and 10 times higher electron and hole mobility (estimated by density functional theory). We show that the principle of this design is not limited to two-dimensional Ge perovskites; we implement it in the case of copper perovskite (also a low-radius metal centre), and we extend it to quasi-two-dimensional systems. We report photodiodes with Ge perovskites that outperform their non-octahedral and lead analogues. The construction of secondary sublattices that interlock with an inorganic framework within a crystal offers a new synthetic tool for templating hybrid lattices with controlled distortion and orbital arrangement, overcoming limitations in conventional perovskites. We report assembly of an organic scaffold within perovskite structures, resulting in the suppression of the lone pair expression of Ge and templating the symmetric octahedra.

[PdCl4]2- dianions are oriented within a crystal in such a way that a Cl of one unit approaches the Pd of another from directly above. Quantum calculations find this interaction to be highly repulsive with a large positive interaction energy. The placement of neutral ligands in their vicinity reduces the repulsion, but the interaction remains highly endothermic. When the ligands acquire a unit positive charge, the electrostatic component and the full interaction energy become quite negative, signalling an exothermic association. Raising the charge on these counterions to +2 has little further stabilizing effect, and in fact reduces the electrostatic attraction. The ability of the counterions to promote the interaction is attributed in part to the H-bonds which they form with both dianions, acting as a sort of glue.[PdCl4]2- dianions are oriented within a crystal in such a way that a Cl of one unit approaches the Pd of another from directly above. Quantum calculations find this interaction to be highly repulsive with a large positive interaction energy. The placement of neutral ligands in their vicinity reduces the repulsion, but the interaction remains highly endothermic. When the ligands acquire a unit positive charge, the electrostatic component and the full interaction energy become quite negative, signalling an exothermic association. Raising the charge on these counterions to +2 has little further stabilizing effect, and in fact reduces the electrostatic attraction. The ability of the counterions to promote the interaction is attributed in part to the H-bonds which they form with both dianions, acting as a sort of glue.

Tetraphenylmethane, tetraphenylsilane, and simple derivatives with substituents that do not engage in hydrogen bonding typically crystallize as close-packed structures with essentially no space available for the inclusion of guests. In contrast, derivatives with hydrogen-bonding groups are known to favor the formation of open networks that include significant amounts of guests. To explore this phenomenon, we synthesized six new derivatives 5a – 5e and 6a of tetraphenylmethane and tetraphenylsilane with urethane and urea groups at the para positions, crystallized the compounds, and determined their structures by X-ray crystallography. As expected, all six compounds crystallize to form porous three-dimensional hydrogen-bonded networks. In the case of tetraurea 5e , 66% of the volume of the crystals is accessible to guests, and guests can be exchanged in single crystals without loss of crystallinity. Of special note are: (i) the use of tetrakis(4-isocyanatophenyl)methane ( 1f ) as a precursor for making enantiomerically pure tetraurethanes and tetraureas, including compounds 5b , 5c ; and (ii) their subsequent crystallization to give porous chiral hydrogen-bonded networks. Such materials promise to include chiral guests enantioselectively and to be useful in the separation of racemates, asymmetric catalysis, and other applications.Key words: crystal engineering, molecular tectonics, hydrogen bonding, networks, porosity, urethanes, ureas, tetraphenylmethane, tetraphenylsilane.

The reaction between two equivalents of dimethyl N-cyanodithioiminocarbonate, [(MeS).sub.2C=N-C[identical to]N] (1), one equivalent of n-butyltin trichloride, Sn(n-Bu)Cl.sub.3 and one equivalent of sodium hydroxide, NaOH led to isolation of a dinuclear complex [Sn(n-Bu)Cl.sub.2(OH)(H.sub.2O)].sub.2 (2) which co-crystallized with four [(MeS).sub.2C=N-C[identical to]N] molecules, [Sn(n-Bu)Cl.sub.2(OH)(H.sub.2O)].sub.2[(CH.sub.3S).sub.2C=N-C[identical to]N].sub.4 (3). The compound was investigated by single-crystal X-ray diffraction analysis and infrared spectroscopy. Compound 3 crystallizes in the triclinic space group P [Formula omitted] with a = 9.8208(15), b = 11.2664(17), c = 12.0446(18) Å, [alpha] = 106.236(5), [beta] = 111.510(5), [gamma] = 97.710(6)°, V = 1147.9(3) Å.sup.3, Z = 1 and Z' = 0.5. In the complex, two aqua-n-butyltinhydroxide dichloride moieties, [Sn(n-Bu)Cl.sub.2(OH)(H.sub.2O)], are bridged by the hydroxides. The hydroxide bridges bond lengths describe a static trans effect yielding a dissymmetry in Sn-O bonding. Two inner O2-H2D[midline horizontal ellipsis]Cl1 hydrogen bonds strengthen the dinuclear component. The dimethyl N-cyanodithioiminocarbonate molecules are linked to the dinuclear component through the hydroxide bridges and the water molecules by O1-H1[midline horizontal ellipsis]N2A and O2-H2C[midline horizontal ellipsis]N2B hydrogen bonding patterns of D type, respectively. The [(MeS).sub.2C=N-C[identical to]N] molecules exhibit a positional disorder. These hydrogen bonding interactions lead to cyclic patterns generating [Formula omitted](6) and [Formula omitted](8) rings. Additional C-H[midline horizontal ellipsis]Cl and C-H[midline horizontal ellipsis]N hydrogen bond patterns also contribute to the crystal structure framework: they give rise to a 3D structure. Graphical Reacting with n-BuSnCl.sub.3 and NaOH in an aqueous mixed solvent, dimethyl N-cyanodithioiminocarbonate, (MeS).sub.2C=N-C[identical to]N forms a co-crystalline 4:1 assembly with the bimetallic organotin(IV) complex, [Sn(n-Bu)Cl.sub.2(OH)(H.sub.2O)].sub.2, whose single crystal XRD analysis exhibits a 3D hydrogen bonded structure.

The reaction between two equivalents of dimethyl N -cyanodithioiminocarbonate, [(MeS) 2 C=N–C≡N] ( 1 ), one equivalent of n -butyltin trichloride, Sn( n -Bu)Cl 3 and one equivalent of sodium hydroxide, NaOH led to isolation of a dinuclear complex {[Sn( n -Bu)Cl 2 (OH)(H 2 O)] 2 } ( 2 ) which co-crystallized with four [(MeS) 2 C=N–C≡N] molecules, {[Sn( n -Bu)Cl 2 (OH)(H 2 O)] 2 [(CH 3 S) 2 C=N–C≡N] 4 } ( 3 ). The compound was investigated by single-crystal X-ray diffraction analysis and infrared spectroscopy. Compound 3 crystallizes in the triclinic space group P 1 ¯ with a  = 9.8208(15), b  = 11.2664(17), c  = 12.0446(18) Å, α  = 106.236(5), β  = 111.510(5), γ  = 97.710(6)°, V  = 1147.9(3) Å 3 , Z  = 1 and Z′ = 0.5. In the complex, two aqua- n -butyltinhydroxide dichloride moieties, [Sn( n -Bu)Cl 2 (OH)(H 2 O)], are bridged by the hydroxides. The hydroxide bridges bond lengths describe a static trans effect yielding a dissymmetry in Sn–O bonding. Two inner O2–H2D⋯Cl1 hydrogen bonds strengthen the dinuclear component. The dimethyl N -cyanodithioiminocarbonate molecules are linked to the dinuclear component through the hydroxide bridges and the water molecules by O1–H1⋯N2A and O2–H2C⋯N2B hydrogen bonding patterns of D type, respectively. The [(MeS) 2 C=N–C≡N] molecules exhibit a positional disorder. These hydrogen bonding interactions lead to cyclic patterns generating R 1 1 (6) and R 2 2 (8) rings. Additional C–H⋯Cl and C–H⋯N hydrogen bond patterns also contribute to the crystal structure framework: they give rise to a 3D structure. Graphical Abstract Reacting with n -BuSnCl 3 and NaOH in an aqueous mixed solvent, dimethyl N -cyanodithioiminocarbonate, (MeS) 2 C=N–C≡N forms a co-crystalline 4:1 assembly with the bimetallic organotin(IV) complex, [Sn( n -Bu)Cl 2 (OH)(H 2 O)] 2 , whose single crystal XRD analysis exhibits a 3D hydrogen bonded structure.

Four silver(I) coordination polymers of composition [Ag 6 (bptp) 3 (OOCCF 2 CF 2 COO) 3 ] ∞ ( 1 ), [Ag 5 (bptp) 2 (CF 3 SO 3 ) 5 (CH 3 COCH 3 ) 2 ] ∞ ( 2 ), [Ag(bmtm)(C 10 H 7 SO 3 )] ∞ ( 3 ), and [Ag 10 (bpte) 4 (NO 3 ) 10 ] ∞ ( 4 ) (bmtm = bis(methylthio)methane, bpte = 1,2-bis(phenylthio)ethane, bptp = 1,3-bis(phenylthio)propane) have been synthesized and structurally characterized. The 2D-coordination networks of both 1 and 2 consist of two meshed networks, (Ag-anion) ∞ and (Ag-ligand) ∞ , which share their silver atoms. The 1D-coordination polymers of 3 are associated through weak van der Waals interactions into 2D network while polymer 4 forms a tubular structure. Relatively short Ag···Ag interactions are found in both 1 and 3 . The stoichiometries of the obtained polymers were found to be independent of the starting materials metal-to-ligand ratio except for coordination polymer 4 . Thermogravimetric analyses of 1 and 2 revealed that they decompose in a single step to metallic silver while 3 and 4 showed a two-step weight loss.

Biguanide groups and biguanidinium cations incorporate multiple sites that can donate or accept hydrogen bonds. To assess their ability to associate and to direct the formation of extended hydrogen-bonded networks, we examined the structure of crystals of four compounds in which two neutral biguanide groups or the corresponding cations are attached to the 1,4- and 1,3-positions of phenylene spacers. As expected, all four structures incorporate extensive networks of hydrogen bonds and reveal other reliable features. In particular, (1) neutral biguanide groups favor a roughly planar conformation with an intramolecular hydrogen bond, and they associate as hydrogen-bonded pairs, (2) despite coulombic repulsion, biguanidinium cations can also associate as hydrogen-bonded pairs, and (3) the 1,3-phenylenebis(biguanidinium) dication favors a pincerlike conformation that allows chelation of suitable counterions. However, the precise patterns of hydrogen bonding in the structures vary substantially, limiting the usefulness of biguanide and biguanidinium as groups for directing supramolecular assembly.Key words: bis(biguanide), bis(biguanidinium), structure, hydrogen-bonded network, noncovalent interaction, supramolecular chemistry, crystal engineering.