Guoping Xue

The synthesis of azacrown ethers with quinoline-based sidearms as potential zinc(II) fluorophores

Abstract Two novel fluorophores, 12 and 13 , composed of diaza-18-crown-6 ligands containing two quinoline-based sidearms which are structurally similar to Zn(II) fluorophores TSQ ( 1 ) and Zinquin ( 2 ) were synthesized as potential Zn(II) fluorophores by reductive amination of 8-benzenesulfonamido-2-quinoline carboxaldehyde 6 and 8-benzenesulfonamido-6-quinolyloxyacetate-2-carboxaldehyde 11 with diaza-18-crown-6 using sodium triacetoxyborohydride (NaBH(OAc)3) as the reducing agent. Preliminary photophysical properties of ligands 12 and 13 show that they possess the properties necessary to be effective chemosensors for Zn2+. The solid state structure of 12 is also reported.

Application of diaza-18-crown-6-capped β-cyclodextrin bonded silica particles as chiral stationary phases for ultrahigh pressure capillary liquid chromatography

Two bonded chiral stationary phases (CSPs), 8-aminoquinoline-2-ylmethyl- and 8-aminoquinoline-7-ylmethyl-diaza-18-crown-6-capped [3-(2-O-beta-cyclodextrin)-2-hydroxypropoxy]propylsilyl silica particles (non-porous, 1.5 microm), have been prepared and evaluated using capillary liquid chromatography at high pressures (> or = 8000 p.s.i.). High column efficiency (up to 400 000 plates m(-1)) was achieved for chiral separations. These CSPs with two recognition sites, i.e. substituted-diaza-18-crown-6 and beta-cyclodextrin combined with high chromatographic efficiency provide good resolution of a variety of enantiomers and positional isomers in relatively short times under reversed-phase conditions. After inclusion of a Ni (II) ion from the mobile phase, the positively charged crown ether-capped beta-cyclodextrin facilitates specific static, dipolar, and host-guest complexation interactions with solutes.

A convenient synthesis and preliminary photophysical study of novel fluoroionophores: macrocyclic polyamines containing two dansylamidoethyl side arms

Abstract A series of novel fluorophores, consisting of macrocyclic polyamines containing two dansylamidoethyl side arms were synthesized as potential zinc (II) fluoroionophores by the reaction of the appropriate macrocyclic polyamines with N-dansylaziridine in acetonitrile at reflux temperature. Preliminary photophysical studies of ligand 3a, 1,7-dimethyl-4,10-bis(dansylamidoethyl)-1,4,7,10-tetraazacyclododecane, 3j, 8,13-bis(dansylamidoethyl)-3-hydroxymethyl-1,3,10-trithia-8,13-diazacyclopentadecane, and their complexes with Cu2+, Zn2+, Cd2+, and Hg2+ are described.

Synthesis of cyclam-capped β-cyclodextrin-bonded silica particles for use as chiral stationary phases in capillary electrochromatography

β-Cyclodextrin (β-CD) was anchored onto silica particles at its C(2) position, derivatized primarily at the C(6) position by treatment with bromoacetyl bromide, and finally reacted with two types of cyclams to form cyclam-capped β-CD-bonded silica particles. When used as chiral stationary phases in capillary electrochromatography, these novel bonded silica particles exhibited excellent enantioselectivities for chiral separations.

Characterization of bis-8-hydroxyquinoline-Armed diazatrithia-16-crown-5 and diazadibenzo-18-crown-6 ligands as fluorescent chemosensors for zinc

Abstract Bis-8-hydroxyquinoline-armed diazatrithia-16-crown-5 ( 1 ) and diazadibenzo-18-crown-6 ( 2a ) ligands selectivity respond to Zn 2+ over other tested metal ions, including Cd 2+ , via large increases in fluorescence, while other side-armed diazadibenzo-18-crown-6 ligands ( 2b – f ) and bis(dansylamidoethyl)-armed 1,8-dimethyltetraza-14-crown-4 ligand ( 3 ) do not respond to tested metal ions via an increase in fluorescence. Ligand 1 forms a 1:1 complex (ML) and a 1:2 complex (M 2 L) with Zn 2+ , and these have emission maxima at different wavelengths (540 and 500 nm, respectively). Due to the large fluorescent enhancement factor of ligand 1 for Zn 2+ , ligand 1 is well suited for use as a fluorescent chemosensor for Zn 2+ .

Synthesis of Diazadi(and tri)thiacrown Ethers Containing Two 5-Substituent(or 2-methyl)-8-hydroxyquinoline Side Arms

Abstract Sixteen new diazadi(or tri)thiacrown ethers containing two 5-substituent(or 2-methyl)-8-hydroxyquino-lin-2-ylmethyl side arms have been prepared by a three-step process. First, the appropriate bis(α-chloroamide)s were treated with five dimercaptans in base to form macrocyclic di(or tri)thiadiamides. The macrocyclic diamides were reduced by BH3-THF to form 1,7-diaza-4-oxa-10,13-dithia-cyclopentadecane (11); 1,7-diaza-4,13-dioxa-10,16-dithiacyclooctadecane (12); 1,7-diaza-4-oxa-10,13,16-trithiacyclooctadecane (13); 1,7-diaza-4,13,16-trioxa-10,19-dithiacycloheneicosane (14); and 1,10-diaza-4,7-dioxa-13,16-dithiacyclooctadecane (15). The diazadi(or tri)thiacrown ethers were then treated with 8-hydroxyquinoline, 8-hydroxy-5-methylquinoline, 5-chloro-8-hydroxyquinoline, and 8-hydroxyquinaldine in the presence of paraformal-delyde in refluxing benzene to form the bis(8-hydroxy-5-substituent(or 2-methyl)quinolin-7-ymethy)-substituted diazadi(or tri)thiacrown ethers 16-31. The crown ethers containing two 8-hydroxyquinoline or 8-hydroxyquinaldine side arms proved to be mixtures of about 90% bis(8-hydroxyquinolin-7-ylmethyl)-substituted crown ethers; 9% mixed (8-hydroxyquinolin-7-ymethyl)-substituted and (8-hydroxyquinolin-5-ylmethyl)-substituted crown ethers; and 1% bis(8-hydroxyquinolin-5-ylmethyl)-substituted crown ethers.

Synthesis of New Crown Ethers Containing Appended Pyridine, 10-hydroxybenzoquinoline, 8-hydroxyquinoline and 2-amino-1-hydroxybiphenyl Sidearms

Twelve crown ethers containing one or two arms were synthesized. Two methods were used to attach arms to the azacrown ethers. Ligands 4 - 12 were prepared by a nucleophilic substitution of secondary macrocyclic amine functions on RX ( X=bromide or tosylate groups). Ligands 13 - 15 were obtained via a Mannich reaction of secondary macrocyclic amines with 5-chloro-8-hydroxyquinoline or a substituted-phenol. Diaza-18-crown-6 was treated with 2-bromomethyl-9-methyl-1,10-phenanthroline at the same conditions in which 4 - 8 and 10 - 12 were prepared. In this case, the main product was the diazacrown ether containing one arm. Twelve new aza-crown ethers bearing aromatic and aliphatic side arms were prepared by nucleophilic substitution by secondary macrocyclic amine functions on halide or tosylates or via a Mannich reaction of the macrocyclic secondary amines with phenolic compounds. R=derivatives of pyridine, 8-hydroxyquiniline, and 1-hydroxybiphenyl. Crown ether include aza-15-crown-5 diaza-18-crown-6 diazatrithia-15 (and 16)-crown-6 and diaza-21-crown-7