The polyfunctional and highly reactive bio-polymer, the chitosan was first regioselectively converted into dialkylated chitosan using dimsyl anionic solution(NaH in DMSO) and bromodecane after protecting amino groups by phthalic anhydride. The dibenzo-18-crown-6-ether, on the other hand, was converted into its carbonyl derivatives via Duff reaction prior to incorporate into chitosan by Schiff b...

A supramolecular poly[3]pseudorotaxane was prepared by self-assembly of a homoditopic cylindrical bis(crown ether) host and a bisparaquat derivative in solution by host-guest complexation.

the complexation reactions between tl+ and pb2+ ions and crown ethers 12-crown-4(12c4), 15-crown-5 (15c5), benzo-15-crown-5 (b15c5), 18-crown-6 (18c6), dicyclohexyl-18-crown-6 (dc18c6) and aza-18-crown-6 (a18c6) were studied in 90% acetonitrile and 90% ethanol solutions at 25 °c, using an a.c. polarographic technique. the stoichiometry and stability of the complexes were determined by monitorin...

The reaction of 4-bromo-aniline, 18-crown-6, and perchloric acid in methanol yields the title compound, C(6)H(7)BrN(+)·ClO(4) (-)·C(12)H(24)O(6), in which the protonated -NH(3) (+) group forms three bifurcated N-H⋯O hydrogen bonds to the O atoms of the crown ether.

In this review, we report DNA duplex-based fluorescence probes/sensors using pyrene monomer-excimer switching. The review mainly comprises two topics: 1) excimer-monomer switching molecular beacons (EMS-MB) and 2) monomer-excimer switching sensors based on the structural motif of antibodies. The EMS-MBs have two pyrene fluorophores connected both at 3' and 5' ends of a single-stranded oligonucl...

In the title compound, [Li(C(8)H(16)O(4))(CD(3)CN)]ClO(4), the Li atom is penta-coordinate. The O atoms of the 12-crown-4 ether form the basal plane, whereas the N atom of the trideutero-aceto-nitrile occupies the apical position. The Li(+) atom is displaced by 0.794 (6) Å toward the apical position from the plane formed by the O atoms because the Li(+) atom is too large to fit in the cavity of...

the do1(18c6)fi (mwli. na. k and i 8c6=18-crown-6) complexes have been chosen as the model systems toinvestigate the nature of chemical bonds between alkali metal cations and large mffitidentaie orgmnic ligands.the b3lyp/6-3i+g(d,p) level of calculation has been used for obtaining equilibrium geernetnes and p(r)functions (electron density distributions). by the aid of fundamental physical theor...

A [3 + 3] modular self-assembly gives rise to the formation of basket-shaped, crown ether-functionalized, nano-sized trimetallo-macrocycles, which function as structural analogues of cyclotriveratrylenes (CTV).

The title compound, C(40)H(40)O(9), is a product of the double crotonic condensation of bis-(2-acetyl-phen-oxy)-3-oxapentane with bis-(2-formyl-phen-oxy)-3,6-dioxaoctane. The title macromolecule includes the 31-crown-7-ether skeletal unit and adopts a saddle-like conformation. The two ethyl-ene fragments have E configurations. The volume of the inter-nal cavity of the macrocycle is approximatel...