Abstract
Based on the hypothesis on the presence of double metal cyanides in the primordial oceans, a series of nano-sized metal(II) hexacyanocobaltate(III) (MHCCo) with the general formula: M3[Co(CN)6]2•xH2O (where M = Zn, Fe, Ni and Mn) has been synthesized. Surface interaction of aromatic amines, namely aniline, 4-chloroaniline, 4-methylaniline and 4-methoxyaniline with MHCCo particles has been carried out at the concentration range of 100–400 μM at pH~7.0. The percentage binding of aromatic amines on MHCCo surface was found to be in the range of 84%–44%. The trend in adsorption was in accordance to the relative basicity of the studied amines. At the experimental pH, amines reacted rapidly with the surface of the iron(II) hexacyanocobaltate, producing colored products that were analyzed by Gas Chromatography Mass Spectroscopy (GC-MS). GC-MS analysis of the colored products demonstrated the formation of dimers of the studied aromatic amines. Surface interaction of aromatic amines with MHCCo was studied by Fourier Transform Infrared (FT-IR) spectroscopy and Field Emission Scanning Electron Microscopy (FE-SEM). The change in amine characteristic frequencies, as observed by FT-IR, suggests that interaction took place through the NH2 group on amines with metal ions of hexacyanocobaltate complexes. FE-SEM studies revealed the adherence of 4-methoxyaniline on zinc hexacyanocobaltate particles surface. We proposed that MHCCo might have been formed under the conditions on primitive Earth and may be regarded as an important candidate for concentrating organic molecules through the adsorption process.
Highlights
Several biologically important molecules such as amino acids, alkaloids and vitamins are found in nature as a source of amines
Four main peaks are assigned to all the metal(II) hexacyanocobaltate(III) (MHCCo) complexes
The peak assignment for the rest of the MHCCo complexes are presented in Table S1 (Supplementary Materials)
Summary
Several biologically important molecules such as amino acids, alkaloids and vitamins are found in nature as a source of amines. Identification of amines in carbonaceous chondritic meteorites (e.g., the Murchison) has been reported by researchers [1,2,3]. The role of amines in catalyzing the formation of sugars from formaldehyde and glycoaldehyde was investigated by Weber [5], whilst the importance of aromatic amines in the formation of polymers containing purines, pyrimidines, amino acids, coenzymes, lipid components and even phosphate was proposed by Nelsestuen [6]. Friedmann and Miller [7] reported the presence of aromatic rings bearing amino acids on primitive Earth. The existence of amines on early Earth is speculated, Inorganics 2017, 5, 18; doi:10.3390/inorganics5020018 www.mdpi.com/journal/inorganics
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
