posted on 2018-07-22, 00:00authored byAbhijit Bera, Balanagulu Busupalli, Bhagavatula L. V. Prasad
Monolayer protected
metal and metal sulfide nanocrystals (NCs)
have mainly two constituents; the inorganic metal or metal chalcogenide
complex as core and organic molecule as shell. Noticing that metal
thiolates have these ingredients inbuilt in their structure, we investigated
them as possible precursors for the preparation of monolayer protected
metal and metal sulfide NCs via solid state grinding method. Accordingly
silver and gold NCs have been prepared using a solvent less green
approach, by the simple and convenient solid state grinding of the
corresponding metal thiolate with sodium borohydride. Similarly, a
large variety of uniform-sized semiconducting NCs of metal sulfides
including PbS, CdS, ZnS, MnS, Ag2S, and CuS could also
be synthesized by the same solid state route by grinding the metal
thiolates with octyl dithiocarbamic acid (C8DTCA) and in
some cases C8DTCA plus small amount of oleylamine as sulfur
source. Interestingly, this simple technique could be used to prepare
sub-3 nm NCs like Ag2S, PbS, and CuS which are otherwise
difficult to prepare by the conventional high temperature solution
routes also. Most gratifyingly, all these NCs, though were prepared
by a solvent less grinding method, could be easily dispersed in nonpolar
solvents as the preparation method ensued the formation of organic
molecule capped NCs.