Two Cu²⁺-specific colorimetric sensors, based on ferrocene-carbohydrate bioconjugates, 2, C₄₆H₅₆O₂₀N₆Fe and 3, C₂₈H₃₃O₁₀N₃Fe were designed and synthesized in good yields. Both the compounds, 2 and 3, behave as very selective and sensitive chromogenic and electrochemical chemosensor for Cu²⁺ ion in aqueous environment (CH₃CN/H₂O (2:8, $v/v$). The analytical detection limit (ADL) for receptor 2 was $7.5 \times 10^{−7}$ M. The considerable changes in their absorption spectra of 2 and 3 are accompanied by the appearance of a new low energy (LE) peak at 630 nm (2: $\epsilon = 1600$ M^-1 cm^-1 and 3: 822 M^-1 cm^-1). This is further accompanied by a strong colour change from yellow to dark green that allows the prospective for `naked eye’ detection of Cu²⁺ ion.

Reactions of $B(C_{6}F_{5})_{3}$ with abnormal N-heterocyclic carbene (aNHC), L1 and cyclic(alkyl)(amino) carbene (cAAC), L2 in the presence of moisture as well as in its absence, have been investigatedin toluene. Reaction of aNHC with 1 equivalent of $B(C_{6}F_{5})_{3}$ under inert condition produced classical Lewisacid-base adduct, [L1. $B(C_{6}F_{5})_{3}$ 1. Further, probing the same reaction with cyclic (alkyl)(amino) carbene(cAAC), having different electronic property, led to the isolation of [L2 $B(C_{6}F_{5})_{3}$, 2 under inert condition.Interestingly, reaction of aNHC or cAAC with 1 equivalent of $B(C_{6}F_{5})_{3}$ in the presence of moisture resulted inwater splitting leading to the formation of [L1-H][(OH) $B(C_{6}F_{5})_{3}$ and [L2-H][(OH) $B(C_{6}F_{5})_{3}$, 4. All thesecompounds (1-4) were characterized in solution by $^{ 1}H$, $^{13}C$, $^{19]F$ and $^{ 11}B$ NMR spectroscopy. Additionally, thesolid-state structures were unambiguously established by crystallographic analysis of compounds 1-4.