An Organic Molecular Nanobarrel that Hosts and Solubilizes C60

<p>Organic cages have gained increasing attention in recent years as molecular hosts and porous materials. Among these, barrel-shaped cages or molecular nano- barrels are promising systems to encapsulate large hosts as they possess windows of the same size as their internal cavity. However, these systems have received little attention and remain practically unexplored de- spite their potential. Herein, we report the design and synthesis of a new trigonal prismatic organic nanobarrel with two large triangular windows with a diameter of 12.7 Å optimal for the encapsulation of C60. Remark- ably, this organic nanobarrel shows a high affinity for C60 in solvents in which C60 is virtually insoluble, providing stable solutions of C60.</p&gt

Cocrystals and Salts of Pyridine-3,5-bis(1-methyl-benzimidazole-2-yl) with Pyromellitic Acid: Aromatic Guest Inclusion and Separation via Benzimidazole–Carboxylic Acid Heterosynthon

An arc-shaped molecule pyridine-3,5-bis­(1-methyl-benzimidazole-2-yl) was shown to form cocrystals and salts with pyromellitic acid (H₄PMA) which are sustained by COOH···N_bim/COO^–···Hbim heterosynthons. The reaction between these two components in the presence of large aromatic guest molecules resulted in the crystals of salts with aromatic inclusion, while the absence of guests resulted in the H₂O and EtOH solvates of cocrystals. The crystal structures of salts exhibited isostructurality with the inclusion of aromatics such as pyrene, perylene, phenanthrene, and 9-anthraldehyde. The crystal structures of solvates were found to differ significantly despite having similar composition. In all these structures the −COOH functional group has exhibited significant preference to interact with the benzimidazole moiety over the pyridine moiety. The aromatic guest inclusion was found to occur via cation···π interactions between the protonated benzimidazole and π-cloud of guest molecules. The competitive experiments on guest inclusion reveal that the two-component host system exhibits selective inclusion of perylene or 9-anthraldehyde over other aromatics such as pyrene or phenanthrene

Interplaying anions in a supramolecular metallohydrogel to form metal organic frameworks

The remarkable effect of anions on the transition from supramolecular gels to crystalline phases has been described. An amino acid-based metallohydrogel was transformed into different metal-organic frameworks through the selective picking of anions. The metallohydrogel and the resulting metal-organic frameworks (MOFs) were thoroughly characterized. The results demonstrated controlled access over the binding of a particular anion to selectively form a particular MOF

A rationally designed thymidine-based self-assembled monolayer on a gold electrode for electroanalytical applications

A self-assembled monolayer (SAM) of 1-(3,5-epidithio-2,3,5-trideoxy-β-D-threo-pentofuranosyl)thymine (EFT) on a gold electrode was prepared and characterized by Raman spectral and electrochemical measurements. Voltammetric and electrochemical impedance measurements show that the SAM of EFT on a Au electrode impedes the electron-transfer reaction. The SAM of EFT was successfully used for the voltammetric sensing of urate in neutral solution. The coexisting ascorbate anion does not interfere and therefore the EFT-based electrode was able to quantify urate at the micromolar level in the presence of a large excess amount of ascorbate. To demonstrate the practical applications, the amount of urate in two different human serum samples was quantified by using the EFT-based electrode; the results are in good agreement with those determined by the clinical method. DFT calculations show that both ascorbate and urate have noncovalent interactions including hydrogen-bonding interactions with EFT

Multistimuli-Responsive Interconvertible Low-Molecular Weight Metallohydrogels and the in Situ Entrapment of CdS Quantum Dots Therein

Two low molecular weight metallohydrogels (ZALA and CALA) have been synthesized from an amino-acid-based ligand precursor (LA) and two different metal salts [zinc acetate dihydrate (ZA) and cadmium acetate dihydrate (CA), respectively. These two hydrogels show a unique chemically stimulated interconversion to each other via a reversible gel–sol–gel pathway. This programmable gel–sol reversible system satisfies logic operations of a basic Boolean logic (INHIBIT) gate. Also, these hydrogels can be degraded into different MOF phases at room temperature spontaneously or in the presence of chloride and bromide salts (NaCl and NaBr.). CdS quantum dots can be grown inside the CALA gel matrix (CdS@CALA) in the presence of small amount of Na₂S. This CdS doped gel exhibits time dependent tunable emission (white to yellow to orange) as a consequence of a slow agglomeration process of the entrapped quantum dots inside the gel matrix. This luminescence property also reflects the corresponding gel derived MOFs (obtained either by self-degradation of CdS@CALA or via anion induction) as well. This, to the best of our knowledge, is probably the simplest way to make a CdS quantum dot based composite material where CdS is entrapped within the gel and the gel-derived MOF matrix