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A new methodology for 2D coordination polymer formation has been reported by in situ amide bond cleavage of the ligand L at room temperature under a mild condition in the presence of aqueous pyridine. The ligand is formed by the coupling of (L)‐valine with benzene‐1,3,5‐tricarboxylic acid (btcH3). The three amide bonds present on the tripodal ligand, easily break and forms 2D coordination polymer with btc−3 as {[(btc)(py)3(H2O)(Co)1.5].(py)(H2O)2}n (1), {(btc)0.66(py)3(H2O)Ni}n (2), and {[(btc)(py)3Zn1.5](H2O)2}n (3). The tripodal ligand L has been characterized by 1H NMR, 13C NMR, IR, and mass spectra and their corresponding coordination polymers 1, 2, and 3, respectively, have been characterized by single‐crystal X‐ray diffraction and thermogravimetric analysis. [ABSTRACT FROM AUTHOR]

Two structurally simple Pt(II)‐directed self‐assembly loop complexes were prepared by reactions of cis‐(PEt3)2Pt(OTf)2 and the corresponding pyridylamide‐functionalized pyridyl ligands. Both Pt(II)‐based complexes exhibit singlet fluorescence, indicating that the platinum metal serves only as a structural, rather than a direct photophysical role within the loop framework. The crystal structure of complex 1 shows a distorted loop conformation with a hydrophobic pocket defined by the bridging ligands. The anion binding affinities of these two complexes were investigated with a range of anions. Such studies using UV–vis absorption, fluorescence, and 1H NMR titrations showed that complex 1 exhibits excellent binding sensitivity and selectivity for benzoate over acetate in solution via a combination of electrostatic, hydrogen‐bonding, and π–π interactions, whereas complex 2 shows comparable binding affinities toward acetate and benzoate due to the lack of favorable aromatic π–π interaction. [ABSTRACT FROM AUTHOR]

Protonation of trans-1,2-bis(4-pyridyl)ethylene (4,4′-bpe) with dilute sulfuric acid (33 %) afforded a protonated adduct [{4,4′-bpe⋅2 H+}2{HSO4}−2{SO4}−2{H2O}2] ( 1). The neighboring olefinic bond in 1 is in a suitable range (3.931-4.064 Å) to undergo a photochemical [2+2] cycloaddition reaction. Upon irradiation with UV light (365 nm), 1 undergoes a molecular sliding involving the 4,4′-bpe⋅2 H+ units, affording 2, stabilized through OSO4⋅⋅⋅π interactions. Heating 1 to 50° C leads to a 3D hydrogen-bonded organic framework (HOF) ( 3). This process occurs through thermal dissociation of the bisulfate anion. Diffusion of iodine through the crystal lattice of 1 and 3 enables the reduction of sulfate to bisulfate, affording a 1D hydrogen-bonded chain ( 4). Solid-state 13C CPMAS NMR, IR, DSC, and powder XRD studies further support stimuli-responsive structural tuning through crystal-to-crystal transformation. All these conversions occur with significant translational and rotational movements along with a series of bond-breaking and bond-forming processes. [ABSTRACT FROM AUTHOR]

The bioinspired design and synthesis of building blocks and their assemblies by the supramolecular approach has ever fascinated scientists to utilize such artificial systems for numerous purposes. Flexibility is a basic feature of natural systems. However, in artificial systems this is difficult to control, especially if there is no preorganization of the component(s) of a system. We have designed and synthesized a series of C3-symmetric N-bridged flexible receptors and successfully utilized them to selectively entrap the notorious and toxic nitrate anion in aqueous medium. This was the first report of highest binding affinity for the nitrate anion in aqueous medium. An impressive self-sorting phenomenon of reversibly formed hydrogen-bonded capsules, which selfassembled from flexible tripodal receptors having branches of similar size and bearing the same amide functionality, has been disclosed. Encapsulated nitrate anion has been further utilized for the photochemical [2+2] cycloaddition reaction for the synthesis of strained four-membered ring structures through dynamic self-assembly. In this Personal Account, we summarize these results showing the utility of naturally inspired flexibility in artificial systems. [ABSTRACT FROM AUTHOR]

A series of neutral C3-symmetric acyclic artificial receptors incorporating amide functionality has been designed, synthesized, and fully characterized. Upon protonation, these conformationally flexible N-bridged tripodal podands 1-5 form in situ cone shape conformation through hydrogen bonding and C-H⋅φ interactions. The protonation-induced interior preorganized cavity is capable of entrapping nitrate anions through the amide N-H bonds to form discrete nitrate complexes (1a-5a), which were fully characterized by NMR, HRESI mass spectra, and single crystal structures. By incorporating suitable fluorophores at each branch of the tripod receptors, the resulting fluorescent receptor 5 selectively recognized nitrate anions by fluorescent quenching in a DMSO solution and displayed one of the highest binding affinities for nitrate anions in polar solvent media by its zwitterionic form. The possible mechanism of proton-induced preorganization of these flexible, acyclic receptors in a convergent cone conformation followed by nitrate complexation has been proposed to rationalize the effective nitrate recognition. [ABSTRACT FROM AUTHOR]

Molecular cavities formed by π‐conjugated component(s) generally, tend to collapse in the absence of guest molecule(s) especially in the solution‐state, because of strong π•••π interactions between molecular components. Recently, we have explored the importance of mutual induced‐fit effect to sort out this issue. In the present report, we have shown the role of substituents on the effectiveness of mutual induced‐fit process in an artificial system. [ABSTRACT FROM AUTHOR]

A series of N-bridgehead tripodal receptors bearing amide functionality is reported which displays reversible binding of nitrate anions viasolvent polarity controlled molecular capsule formation through a dynamic self-assembly process. [ABSTRACT FROM AUTHOR]

A trinuclear star-shaped organometallic host with a π-acidic interior cavity has been synthesized and this shows a strong anion-π interaction with PF6-, as demonstrated in the crystal structure and colorimetric and luminescent responses with F- anion in solution. [ABSTRACT FROM AUTHOR]

Review: [57 refs. [ABSTRACT FROM AUTHOR]

A trinuclear star-shaped organometallic host with a pi-acidic interior cavity has been synthesized and this shows a strong anion-pi interaction with PF6-, as demonstrated in the crystal structure and colorimetric and luminescent responses with F- anion in solution.

Mercuric chloride can readily enter into the biological cycle where it gets converted into other forms of mercury and causes severe neurotoxic, genotoxic and immunotoxic effects; a number of tripodal ligands have been synthesized that selectively bind mercuric chloride and in the presence of AgPF6, mercury can be removed and supramolecular complexes of the PF6- anion are formed.

Primary cardiac lymphomas are rare lesions in children with acquired immunodeficiency syndrome (AIDS). Most of them are high-grade Burkitt's or Burkitt-like lymphomas. They usually present with congestive cardiac failure, pericardial effusion or tamponade, arrhythmias, with predominant systemic 'B' symptoms and often with widespread extranodal involvement. The clinical profile and operative and pathological findings of a 4-year-old boy with AIDS-associated Burkitt's lymphoma of the heart presenting with acute right heart failure and fatal secondary pulmonary hypertension is reported.