2D amphiphilic organoplatinum(ii) metallacycles: their syntheses, self-assembly in water and potential application in photodynamic therapy

Two 2D amphiphilic organoplatinum(ii) metallacycles with a porphyrin unit as the core and hydrophilic glycol units as the tail were designed and fabricated successfully through a new method called "coordination-driven self-assembly". They can self-assemble into micelles in water and have potential applications in photodynamic therapy.

Carbohydrate Derived Organogelators and the Corresponding Functional Gels Developed in Recent Time

Owing to their multifarious applicability, studies of molecular and supramolecular gelators and their corresponding gels have gained momentum, particularly in the last two decades. Hydrophobic⁻hydrophilic balance, different solvent parameters, gelator⁻gelator and gelator⁻solvent interactions, including different noncovalent intermolecular interactive forces like H-bonding, ionic interactions, π⁻π interactions, van der Waals interactions, etc., cause the supramolecular gel assembly of micro and nano scales with different types of morphologies, depending on the gelator, solvent, and condition of gelation. These gel structures can be utilized for making template inorganic superstructures for potential application in separation, generation of nanocomposite materials, and other applications like self-healing, controlled drug encapsulation, release and delivery, as structuring agents, oil-spill recovery, for preparation of semi-conducting fabrics, and in many other fields. Sugars, being easily available, inexpensive, and nontoxic natural resources with multi functionality and well-defined chirality are attractive starting materials for the preparation of sugar-based gelators. This review will focus on compilation of sugar derived organogelators and the corresponding gels, along with the potential applications that have been developed and published recently between January 2015 and March 2018.

Guanosine-Derived Supramolecular Hydrogels: Recent Developments and Future Opportunities

Hydrogels are attractive materials for designing sensors, catalysts, scaffolds for tissue engineering, stimuli responsive soft materials, and controlled-release drug delivery systems. In recent years, self-assembly of guanosine and its derivatives has received immense interests for devising programmable supramolecular biomaterials including hydrogels. This perspective highlights some of the history and the recent developments of guanosine-based supramolecular hydrogels and their applications. Future prospects and scope of the guanosine-based hydrogels have also been discussed.

A new nitrogen rich open chain diazine ligand system: synthesis coordination chemistry and magneto-structural studies

The synthesis and coordination chemistry of a new series of open chain diazine based ligands (L3aH₂, L3bH₂, and L3cH₂) is reported. The ligands comprise a central disubstituted bipyridine moiety with two bridging alkoxide oxygen donors, together with diazine and pyridine terminal groups strategically located to coordinate three metal centres. Reactions of L3aH₂ and L3bH₂ with CuX₂ (X^- = ClO₄, Cl, NO₃) yield a trinuclear complex (1) and 1-D copper chains (2, 3). In these complexes the ligands bind copper ions via N_bipyridne, trans N_diazine, O_hydrazone, and N_pyridne donors while vacant sites are occupied by counter ions or solvent molecules (methanol, water, acetonitrile). Reaction of L3cH₂ with MnCl₂ affords a linear trinuclear Mn complex (4), where the Mn(ii) ions are connected via μ₂-O_hydrazone linkers with no N-N bridging. Reaction of L3aH₂ with Fe(SO₃CF₃)₂ yields a tetranuclear mixed valence Fe complex (5), in which both trans N-N and O_hydrazone bridging is observed. Magnetic studies reveal the presence of moderate to strong antiferromagnetic interactions in complexes 1-4 while a mix of ferromagnetic and antiferromagnetic interactions is observed in complex 5.

N Donor substituted acetylacetones – versatile ditopic ligands

Acetylacetone (2,4-pentanedione) derivatives with N donor substituents represent ditopic ligands with coordination sites of distinctly different Pearson hardness. Deprotonation of the acetylacetone (Hacac) moiety leads to O,O′ chelating monoanionic (acac) ligands suitable for coordination to hard cations. The softer N donor site(s) preferably act as nucleophiles towards softer partners. When the organic molecules are employed as linkers and coordinate via either site, they are often selective and allow to synthesize well-ordered heterometallic solids. This review addresses the derivatives of 17 pentanediones with nitrile, pyridyl and pyrazolyl moieties as N donor substituents, with an emphasis on structurally characterized compounds. Depending on the N donor substituents and the cations, O,O′ or N coordination will dominate. The nitrile-substituted compounds essentially behave as acetylacetones; they may easily O,O′ coordinate to a wide range of cations whereas N coordination is limited to AgI, CuI or, in the case of less soft cations, to longer and presumably weaker contacts, e.g. to the more distant sites in Jahn–Teller distorted CuII. In contrast, pyridyl-substituted pentanediones act as N donor ligands, regardless whether their (H)acac site is chelating a cation or not. The still scarcely explored pyrazolyl derivative shows the most complex coordination pattern: it may be deprotonated both at the acetylacetone and the pyrazol site, the latter affording N,N′ bridging ligands. In addition to N donor nucleophilicity, the distance between the alternative coordination sites and their mutual orientation are relevant for crystal engineering applications.

Controlled formation of ordered coordination polymeric networks using silsesquioxane building blocks

In this report, we synthesized ordered coordination polymers using polyhedral oligomeric silsesquioxanes (POSS) as a building block. A POSS with eight carboxylic terminals was coordinated with copper ions at various temperatures, forming polymeric networks. This novel coordination polymer has a long-range ordered structure.

Pyridine/pyridinium symmetrical bisamides as functional materials: aggregation, selective sensing and drug release

We report the design, synthesis and gelation behavior of some 3-amino pyridine/pyridinium-based bisamides. As an application, gels are useful in the visual detection of cations, anions, biomolecules and in drug release.

Extended lead(ii) architectures engineered via tetrel bonding interactions

The cooperative action of multiple non-covalent interactions allowed for the assembly of a new series of Pb^II coordination compounds.

Novel 1D coordination polymers built from acyclic cryptate containing bis(1H-1,2,4-triazole) ligands and featuring coordinated counteranions

Two new coordination polymers, namely, ZnL₂(BF₄)₂ (1) and CuL₂(NO₃)₂ (2) were constructed from a new flexible acyclic cryptate-bis(1H-1,2,4-triazole) ligand.

Synthesis, crystal structure, fluorescence properties of 1D chain Manganese (II) and Cadmium (II) complexes

Two complexes, {[Mn(3-pmpmd)₂(Cl)₂]·2H₂O}_n(1), {[Cd(3-pmpmd) (I)₂]·CHCl₃·H₂O}_n(2), (3-pmpmd, N,N'-bis(3-pyridylmethyl)pyromellitic diimide) were synthesized and characterized by elemental analyses, IR spectroscopy, thermogravimetric analyses, and X-ray single-crystal structure analysis. The conformations of 3-pmpmd ligand affect their structural diversity. Complex 1 is a 1D double chain structure in edge-to-edge arrangement by π⋯π interactions. Complex 2 is a typical 1D zigzag chain structure arranged in a parallel array containing 1D channel to accommodate the chloroform and water guest molecules. Thermal stabilities and fluorescence properties of both complexes were investigated. The solution of complex 2 in DMF can sense for I^- anion by quenching fluorescence intensity, whereas other anions increasing fluorescence intensity.

Shape Memory Polymers Based on Supramolecular Interactions

Shape memory polymers (SMPs), with the capability to change from one or more temporary shapes to predetermined shapes in response to an external stimulus, have attracted much interest from both academia and industries. When introducing supramolecular interactions that have been featured as dynamic and reversible into the design of novel SMPs, intriguing and unique functionalities have been engendered and thereby broaden the potential applications of the SMPs to new territories. In this review, we summarize recent progress made in SMPs based on supramolecular interactions, provide insight into the material design and shape memory mechanism, elucidate and evaluate their properties and performance, and point out opportunities and applications of SMPs.

Synthesis, characterization and magnetic studies on mono-, di-, and tri-nuclear Cu(ii) complexes of a new versatile diazine ligand

The synthesis and coordination chemistry of a new open-chain diazine ligand (L4H₂) containing bipyridine, oxime and hydrazone functionalities is reported. Reaction of L4H₂ with CuCl₂·2H₂O affords the mononuclear complex [Cu(L4H₂)Cl₂] (1) in which the ligand acts as a neutral tridentate N,N',N'' donor, whereas treatment with a large excess of CuCl₂·2H₂O affords the dinuclear complex [Cu₂(L4H)Cl₃(CH₃OH)(H₂O)] (2) in which the ligand is singly-deprotonated at the diazine, offering N,N',N'' and N,N' donor sets to two Cu(ii) ions. Reaction with Cu(NO₃)₂·3H₂O yields the trinuclear complex, [Cu₃(L4H)₂(CH₃OH)₄(NO₃)₄] (3) in which the ligand is again singly deprotonated, but now presents a tetradentate N,N',N'',N'''-donor set to the first Cu(ii) and behaves as an N,O-chelate to a second Cu(ii), with a conformational change from cis to trans at the diazine moiety. When the latter reaction is repeated in the presence of a mild base, a second trinuclear complex is isolated, [Cu₃(L4)₂(CH₃CH₂OH)](NO₃)₂ (4) in which both the diazine and oxime functionalities of the ligand are deprotonated which subsequently bridges all three Cu(ii) ions, acting as an N,N',N'' donor to the first Cu(ii), a N,N' donor to a second Cu(ii) (similar to 2) and as a terminal O-donor to a third Cu(ii) ion. The Cu(ii) ions are linked mutually cis via the two-atom diazine bridge in the case of 2 and 4 and trans in the case of 3. Magnetic studies reveal the presence of weak ferromagnetic interactions in 2 (g = 2.2, J/k = +12.8 K) and strong antiferromagnetic interactions in both 3 and 4 (g = 2.093 J/k = -140 K and g = 2.24 J/k = -300 K respectively).

Two novel supramolecular metallogels constructed by platinum(ii) coordination and pillar[5]arene-based host–guest interactions

Two multi-responsive supramolecular metallogels were constructed by coordination-driven self-assembly, host–guest interaction and supramolecular polymerization.

Ligand and solvent effects in the formation and self-assembly of a metallosupramolecular cage

A metallosupramolecular cage and a one-dimensional coordination polymer have been synthesized and structurally characterized by single crystal X-ray diffraction.

Crystal engineering of a series of complexes and coordination polymers based on pyrazole-carboxylic acid ligands

Three new complexes and two coordination polymers have been synthesized.

A Zn(ii) complex with large channels based on 3′-nitro-biphenyl-3,5,4′-tricarboxylic acid: synthesis, crystal structure, fluorescence sensing of ATP, ADP, GTP, and UTP in aqueous solution and drug delivery

A 3D Zn(ii)–MOF with large cubic channels was synthesized. It showed fluorescence sensing of ATP, ADP, GTP, and UTP. Furthermore, it exhibited a remarkable capacity for and controlled release of 5-fluorouracil.

A supramolecular polymer network gel with stimuli-responsiveness constructed by orthogonal metal ion coordination and pillar[5]arene-based host–guest recognition

A novel external stimuli-responsive supramolecular polymer network gel was fabricated by orthogonal Ag-coordination and pillar[5]arene-based host–guest interactions.

Persistence of C–H⋯π(chelate ring) interactions in the crystal structures of Pd(S2COR)2. The utility of Pd(S2COR)2as precursors for palladium sulphide materials

The influence of C–H⋯π(PdS₂C) interactions in the molecular packing of Pd(S₂COR)₂increases as the steric bulk ofRincreases.

Rational construction of functional molybdenum (tungsten)–copper–sulfur coordination oligomers and polymers from preformed cluster precursors

Discrete Mo(W)–Cu–S clusters are used as precursors and building blocks for a diverse array of cluster-supported coordination oligomers and polymers.

Coordination polymers built from 1,4-bis(imidazol-1-ylmethyl)benzene: from crystalline to amorphous

A review of the different crystalline and amorphous coordination polymers (CPs) built from 1,4-bis(imidazol-1-ylmethyl)benzene (bix) is presented, with special emphasis on the large variety of structures reported so far and their potential applications.

Multifarious facets of sugar-derived molecular gels: molecular features, mechanisms of self-assembly and emerging applications

The remarkable capability of nature to design and create excellent self-assembled nano-structures, especially in the biological world, has motivated chemists to mimic such systems with synthetic molecular and supramolecular systems. The hierarchically organized self-assembly of low molecular weight gelators (LMWGs) based on non-covalent interactions has been proven to be a useful tool in the development of well-defined nanostructures. Among these, the self-assembly of sugar-derived LMWGs has received immense attention because of their propensity to furnish biocompatible, hierarchical, supramolecular architectures that are macroscopically expressed in gel formation. This review sheds light on various aspects of sugar-derived LMWGs, uncovering their mechanisms of gelation, structural analysis, and tailorable properties, and their diverse applications such as stimuli-responsiveness, sensing, self-healing, environmental problems, and nano and biomaterials synthesis.