Single-crystals X-ray structure analysis of very thermally labile and moisture sensitive ammoniate crystals of [K0.28Rb7.72Si9Ni(CO)2]2·16NH3 show the presence of the very rarely observed nickel-silicide complex [{Ni(CO)2}2(μ-Si9)2]8−, which was up to now only known in the 18-crown-6 involving solid [Rb@18-crown-6)]2[K@18-crown6)]2Rb4[{Ni(CO)2}2(μ-Si9)2]·22NH3. This shows that, like already kno...

Restorations of 98 implant-supported single crowns in anterior maxillary area were divided into 5 groups: zirconia abutment, titanium abutment, and gold/gold hue abutment with zirconia coping, respectively, and titanium abutment with metal coping as well as gold/gold hue abutment with metal coping. A reflectance spectrophotometer was used to evaluate the color difference between the implant cro...

A 1,2-bis(pyridinium)ethane type axle containing a terpyridine chelate group, when combined with 24-membered crown ethers, forms [2]pseudorotaxanes, the stability of which can be controlled by coordination of metal ions with different geometries.

An overall treatment with dental implant consist of several essential parts, including a superstructure containing fixture (part of the implant embedding in the bone), abutment (a machined tapered prepared superstructure attached to the fixture), a retainer (which hold the aesthetic portion of the restoration) and the crown (aesthetic part of the restoration). In this common kind of restoration...

The discovery of the crown ethers stemmed from efforts to control the catalytic activity of vanadium and copper by complexation with multidentate ligands. The first crown ether, 2,3,11,12-dibenzo-1,4,7,10,13,16-hexaoxacyclo-octadeca-2,11-diene, was obtained in 0.4% yield during an attempt to prepare a phenolic ligand from catechol and bis(2-chloroethyl)ether. This compound, which complexed with...

A new functional low molecular-weight gelator (LMWG) based on crown-appended quaterthiophene was synthesized and investigated as a new alkali metal cation responsive material with enhanced fluorescence emission upon gel-to-sol phase transition.

A novel bilayer metal-organic framework is assembled with a perfect intralayer triangular subnet and ideal interlayer Td arrangement between unprecedented crown-like Co7 cluster units, exhibiting high spin frustration.

Via the self-assembly of two bis(meta-phenylene)-32-crown-10-based cryptands, bearing covalent and metal complex (ferrocene) linkages, with dimethyl paraquat, novel [3]pseudorotaxanes were formed statistically and anticooperatively, respectively.

OBJECTIVES The aim of this study was to evaluate the clinical performance of posterior, metal-free polymer crowns with and without a glass-fiber framework, in comparison to metal-ceramic crowns. METHODS After randomisation, 80 single crowns, manufactured from a newly designed polymer composite, were set in posterior teeth. Half of these received a glass-fiber framework, while half were prepar...

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...