Characterization Of Crown Ether, Cucurbituril Supramolecules And Nanocrystalline Zinc Deposit

This paper can be divided into three parts. The first part is characterization of cucurbituril supramolecular complexes in gas phase using Fourier transform ion cyclotron resonance electrospray ionization mass spectrometry. cucurbituril[5] can bind with ammonium or alkali metal ions to capture guest molecules with right size inside its hollow cavity. For those guest molecules with too large size such as ethanol or benzene; as well as those with too small size such as hydrogen or helium; the cucurbituril [5] can not capture them inside the hollow cavity, which shows a very high size selectivity. Collisional induced dissociation technique is applied to characterize cucurbituril supramolecule structures complexed with 1,4-diaminobutane, phenylenediamine and lysine. The supramolecules shows wheel-and-axle architechtures, which means the line-shaped guest molecules are threaded through cucurbituril[6]. cucurbituril[7] and cucurbituril [8] are observed to be able to contain larger guest molecules compared to cucurbituril [6], such as N,N -dimethyl-4,4 -bipyridinium or cyclam, even to form a "Russian Doll" structure.The second part introduces a new method to determine the binding constants of ether-alkali metal cation complexes by ion trap electrospray ionization mass spectrometry. A complex ([18-crown-6 + K]+) with a known binding constant value is used as a reference. Then a second host dibenzao-18-crown-6 or guest Na+is added to compete with reference host or guest. On the basis of the change in intensity of the reference complex, the binding constant is then derived for the complex of interest using a set of simultaneous equilibrium equations. The logarithm value of binding constants of [18-crown-6 + Na]+ [dibenzao-18-crown-6+K] +and [dibenzao-18-crown-6+Na]+ are determined to be 4.5 4.9 and 4.4, which agree with the reported literature values and validate this method.In the third part, The corrosion inhibition properties of pyridine and its derivatives for nanocrystalline zinc deposit in HC1 and NH4CI solutions were determined using weight loss method .The effect of pyridine and its methyl derivatives and bromo-hexadecal pyridine on the inhibition properties for the nanocrystalline zinc deposit wasstudied. In HCl solution, the corrosion resistance of nanocrystalline zinc deposit is better than that of common zinc metal. In a certain condition, the corrosion inhibition properties of 2-methyl-pyridine 4-methyl-pyridine pyridine and 3-methyl-pyridine goes up respectively. The inhibition mechanism of these compounds is explained using the calculating results of ab initio RHF/6-31G(d) and MNDO.