title: MnO2 nanostructures of different morphologies from amino acids-MnO4- reactions in aqueous solutions.
abstract: In this paper, we describe a simple method for the synthesis of MnO(2) nanostructures (quantum dots) by permanganate oxidations of methionine and cysteine. Upon addition of permanganate to a solution of reductant (methionine and/or cysteine), yellow-brown color species appears within the time of mixing which was stable for several weeks. The UV-vis spectroscopy and transmission electron microscopy (TEM) techniques were used to characterize the nature of color formed. TEM images show that the MnO(2) sol consists of aggregated spherical nonoparticles (size in the range ca<or=7 nm) of various forms. In addition, we observed the different morphologies of the MnO(2) nanostructures (MnO(2) nanoparticles, nanosheet, and fiber-like aggregated nanostructures) under different experimental conditions. The effect of various parameters, such as [H(+)], [MnO(4)(-)], and [reductants] was also investigated.
authors.affiliation: Department of Chemistry, Faculty of Science, King Abdul Aziz University, PO Box 80203, Jeddah 21413, Saudi Arabia. drkhanchem@yahoo.co.in
authors.forename: Zaheer
authors.initials: Z
authors.lastname: Khan
authors.forename: Shaeel
authors.initials: S
authors.lastname: Ahmed Al-Thabaiti
authors.forename: Abdullah
authors.initials: A
authors.lastname: Yousif Obaid
authors.forename: Ziya Ahmad
authors.initials: ZA
authors.lastname: Khan
mesh_terms: D000465:Algorithms; D000596:Amino Acids / Q000737:chemistry*; D003545:Cysteine / Q000737:chemistry; D017895:Manganese Compounds / Q000737:chemistry*; D008715:Methionine / Q000737:chemistry; D046529:Microscopy, Electron, Transmission; D008956:Models, Chemical; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure; D010084:Oxidation-Reduction; D010087:Oxides / Q000737:chemistry*; D012996:Solutions / Q000737:chemistry; D013053:Spectrophotometry; D014867:Water / Q000737:chemistry
chemical_list: D000596:Amino Acids; D017895:Manganese Compounds; D010087:Oxides; D012996:Solutions; D014867:Water; C048856:permanganic acid; D008715:Methionine; D003545:Cysteine; C016552:manganese dioxide