Definitely the pH plays a role and often copper is reduced from the sulfate by going via the tetraammine complex (i.e. in alkaline solution) whereas the chloride is obviously quite acidic. The reducing agent is also important - what are you using? Citrate, ascorbic acid, hydrogen, hydrazine hydrate, NaBH4 are all possible candidates. The concentration is another key parameter both of precursor copper salt and of the reducing agent.

Thanks for the answer, Dr. Rawle.

To be quite frank, I have tried numerous methodologies, varying several experimental parameters, such as: concentration of precursor (CuSO4 in all cases), concentration of reducing agent (NaBH4, Ascorbic acid), pH of the solution (from acidic to basic), temperature and capping agents (from citrates, tartatarates to polymeric ones). The degree of success in each batch varied largely.

My doubt lies specifically in substituting a copper precursor employed in a given methodology reported in the literature for another and the impact that this may cause. Part of your answer " often copper is reduced from the sulfate by going via the tetraammine complex (i.e. in alkaline solution) whereas the chloride is obviously quite acidic " may help in future decision making regarding further experiments.

Kind regards.

In many cases the anions are found passivating some crystal facets, therefore different anions may allow different anisotropic growth. Note that the real picture in terms of crystal growth may be much more complicated.

To give you an example, some metal halides form lamelar structures with primary amines which can be converted into two-dimensional metal chalcogenides. However, the lamelar structures cannot be formed with any counter ion!

I think that soon a review on the role of halides in nanocrystal growth is coming out (keep an eye on Liberato Manna's publications)

Cheers

G