Tectons In Crystal Engineering Research Articles

The Isocyanide Complexes cis-[MCl2(CNC6H4-4-X)2] (M = Pd, Pt; X = Cl, Br) as Tectons in Crystal Engineering Involving Halogen Bonds

The isocyanide complexes cis-[MCl2(CNC6H4-4-X)2] (M = Pd; X = Cl, Br; M = Pt; X = Br) form isomorphous crystal structures exhibiting the Cl/Br and Pd/Pt exchanges featuring 1D chains upon crystallisation. Crystal packing is supported by the C–X···X–C halogen bonds (HaBs), C–H···X–C hydrogen bonds (HB), X···M semicoordination, and C···C contacts between the C atoms of aryl isocyanide ligands. The results of DFT calculations and topological analysis indicate that all the above contact types belong to attractive noncovalent interactions. A projection of the electron localization function (ELF) and an inspection of the electron density (ED) and the electrostatic potential (ESP) reveal the amphiphilic nature of X atoms playing the role of HaB donors, HaB and HB acceptors, and a nucleophilic partner in X···M semicoordination.

Chiral Triphenylacetic Acid Esters: Residual Stereoisomerism and Solid-State Variability of Molecular Architectures.

We have proven the usability and versatility of chiral triphenylacetic acid esters, compounds of high structural diversity, as chirality-sensing stereodynamic probes and as molecular tectons in crystal engineering. The low energy barrier to stereoisomer interconversion has been exploited to sense the chirality of an alkyl substituent in the esters. The structural information are cascaded from the permanently chiral alcohol (inducer) to the stereodynamic chromophoric probe through cooperative interactions. The ECD spectra of triphenylacetic acid esters are highly sensitive to very small structural differences in the inducer core. The tendencies to maximize the C–H···O hydrogen bonds, van der Waals interactions, and London dispersion forces determine the way of packing molecules in the crystal lattice. The phenyl embraces of trityl groups allowed, to some extent, the control of molecular organization in the crystal. However, the spectrum of possible molecular arrangements is very broad and depends on the type of substituent, the optical purity of the sample, and the presence of a second trityl group in the proximity. Racemates crystallize as the solid solution of enantiomers, where the trityl group acts as a protecting group for the stereogenic center. Therefore, the absolute configuration of the inducer is irrelevant to the packing mode of molecules in the crystal.

Multidentate, V-Shaped Pyridine Building Blocks as Tectons for Crystal Engineering.

The formation of supramolecular structural units through self-assembly is a powerful method to design new architectures and materials endowed with specific properties. With the aim of adding a group of versatile tectons to the toolkit of crystal engineers, we have devised and synthesised four new V-shaped building blocks characterised by an aryl acetylene scaffold comprising three substituted pyridine rings connected by two triple bonds. The judicious choice of different substituents on the pyridine rings provides these tectons with distinctive steric, electrostatic and self-assembly properties, which influence their crystal structures and their ability to form co-crystals. Co-crystals of the tectons with tetraiododifluorobenzene were obtained both via traditional and mechanochemical crystallisation strategies, proving their potential use in crystal engineering. The energetic contributions of the supramolecular interactions at play in the crystal lattice have also been evaluated to better understand their nature and strength and to rationalise their role in designing molecular crystals.

Crystal engineering with palladium(II)-based self-assembled binuclear complexes as tectons

A series of binuclear palladium(II)-based self-assembled metallomacrocycles of Pd2L′2L2 type compositions were synthesized by complexation of an imidazole appended non-chelating bidentate ligand L with different cis-protected palladium(II) components (i.e. PdL′). The complexes [Pd2(en)2(L)2](NO3)4, 1, [Pd2(tmeda)2(L)2](NO3)4, 2, [Pd2(bpy)2(L)2](NO3)4, 3, and [Pd2(phen)2(L)2](NO3)4, 4 were characterized by NMR spectroscopy and their nuclearities were established with the help of ESI-MS. Solid state structures of the complexes 2, 3 and [Pd2(phen)2(L)2](OTf)4, 4′, were established by the single-crystal XRD technique. These metallomacrocycles could act as tectons for crystal engineering by using the available π-surface on their architectures. The crystal packing of these molecules revealed the importance of the π-surface on the ligand moiety as well as on the cis-protecting moiety. Utilization of the π-surfaces afforded 1D to 3D supramolecular networks in solid state.

Cis-Protected palladium(ii) based binuclear complexes as tectons in crystal engineering and the imperative role of the cis-protecting agent

The shape and molecular packing of cis-protected Pd(ii) based binuclear complexes depends upon the ligand and cis-protecting agents.

Bandgap Engineering in π-Extended Pyrroles. A Modular Approach to Electron-Deficient Chromophores with Multi-Redox Activity.

A family of bandgap-tunable pyrroles structurally related to rylene dyes was computationally designed and prepared using robust, easily scalable chemistry. These pyrroles show highly variable fluorescence properties and can be used as building blocks for the synthesis of electron-deficient oligopyrroles. The latter application is demonstrated through the development of π-extended porphyrins containing naphthalenediamide or naphthalenediimide units. These new macrocycles exhibit simultaneously tunable visible and near-IR absorptions, an ability to accept up to 8 electrons via electrochemical reduction, and high internal molecular free volumes. When chemically reduced under inert conditions, the most electron-deficient of these macrocycles revealed reversible formation of eight charged states, characterized by remarkably red-shifted optical absorptions, extending beyond 2200 nm. Such features make these oligopyrroles of interest as functional chromophores, charge-storage materials, and tectons for crystal engineering.

C3-symmetric trinuclear copper(ii) species as tectons in crystal engineering

Three new complexes have been obtained using C3-symmetric trinuclear complexes as tectons; [Cu3(felden)(NCS)3(dmf)3] (1), [Cu3(felden)(mand)3]·(C2H5)2O (2), and [Cu3(felden)(dca)3(C2H5OH)]·2H2O (3) (H3felden is the Schiff base resulting from the condensation of 2,4,6-triformylphloroglucinol with N,N-dimethylethylenediamine, mand− is the anion of the R-mandelic acid and dca− is the dicyanamide anion). Compounds 1 and 2 are discrete trinuclear species, while compound 3 is a 2D coordination polymer, constructed from trinuclear nodes and dicyanamido spacers. The variable-temperature magnetic properties of 1–3 have been investigated and they reveal the occurrence of weak antiferromagnetic interactions between the copper(II) ions (−J values ranging from 0.90 to 2.40 cm−1) whose size and trend are dependent on the intramolecular copper–copper separation and nature of the basal chromophore at each copper atom.

ChemInform Abstract: Compartmental Schiff‐Base Ligands — A Rich Library of Tectons in Designing Magnetic and Luminescent Materials

AbstractReview: 47 refs.

Compartmental Schiff-base ligands—a rich library of tectons in designing magnetic and luminescent materials

The binuclear complexes (3d-3d, 3d-3d', 3d-4f) with compartmental ligands can efficiently act as tectons in crystal engineering. Various high nuclearity clusters and coordination polymers can be easily obtained by choosing the appropriate spacers. The main interest in such systems arises from their magnetic and photophysical properties. Moreover, 3d-3d' and 3d-4f complexes are useful precursors in designing heterotrimetallic systems with relevance in molecular magnetism.

Oligonuclear Complexes as Tectons in Crystal Engineering: Structural Diversity and Magnetic Properties

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Oligonuclear complexes as tectons in crystal engineering: structural diversity and magnetic properties

This article focuses on the employment of bi- and trinuclear complexes as building blocks in designing novel heterometallic systems. A large variety of polynuclear complexes, ranging from high-nuclearity clusters to high-dimensionality coordination polymers, can be constructed by taking advantage of the high flexibility of the multimetallic nodes. The following oligonuclear complexes are currently used as tectons in our laboratory: (a) bis(alkoxo)-bridged copper(ii) species; (b) homobinuclear species with metal ions held together by end-off, or macrocyclic compartmental ligands; (c) heterometallic complexes with dissymmetric compartmental ligands. The 3d-4f nodes are particularly interesting since the metal ions interact selectively with various spacers. The intra-node exchange interactions, as well as those between the resulting spins, generate interesting magnetic properties.

Synthesis of m‐Terphenyl Derivatives for Potential Use as Tectons in Crystal Engineering.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Synthesis of m-terphenyl derivatives for potential use as tectons in crystal engineering

Treatment of 4,4-biphenyldiboronic acid with suitably substituted iodo- m-terphenyls provide easy access to the precursors for the synthesis of two rigid m-terphenyl derivatives bearing, H-bonding groups, for potential use as tectons in crystal engineering.

Synthesis and use of poly-pyridyl tectons in crystal engineering

Synthesis and use of poly-pyridyl tectons in crystal engineering