Four aqueous systems with copper(II) acetate and sodium hexanoate L$^1$, differing in pyridine derivatives (2-aminopyridine L$^2$, 2-hydroxypyridine L$^3$, 3-hydroxypyridine L$^4$, and nicotinamide L$^5$) were prepared. These were applied at five different concentrations. Due to the observed color and IR spectra of the solid products it is estimated that L$^3$ does not bind, but turquoise-green [Cu$_2$(L$^1$)$_4$]$_n$ is precipitated. Blue [Cu(L$^1$)$_2$(L$^4$)$_2$]$_n$ was obtained with L$^4$. The structure varies between blue [Cu(L$^1$)$_2$(L$^2$)$_2$] at the highest concentration, green [Cu(L$^1$)$_2$(L$^2$)], and then turquoise [Cu$_2$(L$^1$)$_4$]$_n$ at the lowest concentration for the L$^2$ system. The blue compounds with L$^5$ have an estimated formula Cu(L$^1$)$_2$(L$^5$)$_2$. The data obtained suggests the compound with L$^4$ or without the pyridine derivative, as they are the least soluble in water, would be most suitable for outdoor conditions. From their different structures, also this aspect may be estimated. Lower solubility (better protection layer) may well be associated with the polymeric nature of the known compounds in these systems.
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