Synthesis of Diferrocenyl Hydrazone–Enone Receptor Molecules – Electronic Communication, Metal Binding, and DFT Study

Abstract

Four new diferrocenyl hydrazone-enone compounds were obtained through a two-step reaction process involving 1,1′-diacetylferrocene, hydrazides, and ferrocenecarboxaldehyde. The structural characterization of two compounds, 6 and 7, through single-crystal X-ray diffraction showed the presence of a stable eclipsed conformation with the two ferrocenyl moieties oriented in trans geometries. The electrochemical and metal-ion sensing properties of the diferrocenyl-bifunctionalized compounds were explored to understand their potential [a]

Selective functionalization of ferrocenyl compounds using a novel solvent free synthetic method for the preparation of bioactive unsymmetrical ferrocenyl derivatives

“…Table shows the selectivity for the formation of mono‐ functionalized product with increasing amount of hydrazide ratio up to 5 equivalents. In our earlier report, we observed the formation of 1a and 1b in much lower yields along with a major amount of symmetrically di‐substituted ferrocenyl compound by solution based method in weakly acidic condition [5a]. The mono‐functionalized compound of the type A are the key precursor for the synthesis of 1,1′‐ unsymmetrically bi‐functionalized ferrocenyl compounds (Type C) which have interesting sensing and electro‐communication properties [5a,6].…”

“…In our earlier report, we observed the formation of 1a and 1b in much lower yields along with a major amount of symmetrically di‐substituted ferrocenyl compound by solution based method in weakly acidic condition [5a]. The mono‐functionalized compound of the type A are the key precursor for the synthesis of 1,1′‐ unsymmetrically bi‐functionalized ferrocenyl compounds (Type C) which have interesting sensing and electro‐communication properties [5a,6]. However, the use of rice husk ash (RHA) as solid support gave highly selective substitution at one of the cyclopentadienyl ring of the ferrocenyl system to obtain compounds 1a , 1b and 2 .…”

“…Recently, ferrocene based organometallic molecular entities have proved their ability by showing inhibitory activities towards several microbes . We have also focused our study on the biological aspects of various ferrocene based molecular systems ranging from ferrocenyl hydrazones, hetero‐bimetallic ferrocenyl chalcones, ferrocene based cluster compounds, ferrocenyl dithiocarboxylates and multi‐ferrocenyl compounds and reported their significant biological properties . Recently, bi‐functionalization of ferrocene in the form of 1,1′‐unsymmetrically di‐substituted derivatives (Figure , Type C) have shown remarkable sensor based, biological and catalytic properties [5a,6].…”

“…We have also focused our study on the biological aspects of various ferrocene based molecular systems ranging from ferrocenyl hydrazones, hetero‐bimetallic ferrocenyl chalcones, ferrocene based cluster compounds, ferrocenyl dithiocarboxylates and multi‐ferrocenyl compounds and reported their significant biological properties . Recently, bi‐functionalization of ferrocene in the form of 1,1′‐unsymmetrically di‐substituted derivatives (Figure , Type C) have shown remarkable sensor based, biological and catalytic properties [5a,6]. However, selective synthesis of these unsymmetrically disubstituted ferrocenyl derivatives has been a challenge due to the formation of symmetrical di‐substituted product (Type A) in major amount, resulting in either very low yield or non formation of the required unsymmetrical derivative of the type B.…”

“…As a result, ferrocenyl compounds containing unsymmetrical substitution (Type C) are far less known than their symmetrical analogue. Nevertheless, we could able to isolate 1,1′‐ unsymmetrically bi‐functionalized ferrocenyl compounds (Type C) involving a two step solution based reaction process,[5a] and observed interesting sensing and electro‐communication properties, but the overall yield of the compounds has been significantly less for any practical application. The low yield has been mainly due to the non‐selective reaction process resulting in reduced formation of the unsymmetrical product (Type B).…”