Ferrocene derivatives constitute an important class of organometallic compounds with not only an extensive range of biological activities but also diverse industrial as well as material science applications. These stimulating features of ferrocene derivatives spurred us to review the recent advances in synthesis methods and biological and other applications reported in the latest literature. An effort has been made to summarize the recent developments in synthetic methods providing access to ferrocene scaffolds and the useful medicinal and material applications, including agricultural, catalytic, polymer, conducting, redox mediating, ferrocenyl stationary phase, rocket propellant and ion sensing applications. Ferrocene-based bulky metallocenes are also discussed.

Recent advances in the synthesis, biological activities and various applications of ferrocene derivatives

Recent research progress in the synthesis and properties of burning rate catalysts based on ferrocene-containing polymers and derivatives

Recent advances in catalytic combustion of AP-based composite solid propellants

Ferrocene-based polymers and their derivatives have the ability to catalyze the burning process of composite solid propellants efficiently. However, the simple and volatile ferrocene migrates to the surface of the solid propellant on prolonged storage, which alters the designed burning parameters and more seriously causes unexpected explosions. To retard migration problems, six novel ferrocene-based polyethyleneimines (PEI-Fcs) were synthesized by the condensation reaction of branched polyethyleneimine (PEI) with ferrocenecarbonyl chloride. The structures of the synthesized PEI-Fcs were characterized using 1H NMR, FT-IR and UV-Vis spectroscopy. The redox properties of the polymers are very important for burning rate catalysts (BRCs). Cyclic voltammetry (CV) revealed that all the PEI-Fcs showed redox properties due to the presence of ferrocene moieties. Migration studies confirmed that the migration of these PEI-Fcs was much slower than that of 2,2-bis(ethylferrocenyl)propane (catocene) and ferrocene. The catalytic effect of PEI-Fcs on the thermal decomposition of ammonium perchlorate (AP) was investigated using thermogravimetry (TG) and differential thermogravimetry (DTG). It was found that in the presence of PEI-Fcs (1–6), the peak decomposition temperature of AP was shifted towards the left (decreased) significantly. The results from the TG and DTG analysis indicated that the novel PEI-Fcs had good catalytic effects of lowering the thermal decomposition temperature of AP and were almost stable up to 220 °C. We expect that these novel PEI-Fcs would have great value as high BRCs for composite solid propellants.

Ferrocene-based polyethyleneimines for burning rate catalysts

Ferrocenyl 1,2,3-triazoles 3a–3f and their Cu(II) or Zn(II) complexes have been synthesized and characterized. Compound 3d was structurally determined by X-ray crystallography. The DTA and TG measurements confirm the obvious catalytic effect of the representative compounds 3a and 3b on the decreasing of the decomposition temperature of ammonium perchlorate (AP) (by 32.3 and 36.2 °C respectively), whereas the Cu or Zn complexes of 3a lowers the thermal decomposition temperature of AP more dramatically, by 60.6 and 61.9 °C respectively. So ferrocenyl 1,2,3-triazoles 3a–3f and their Cu(II) or Zn(II) complexes are a kind of potentially high-burning-rate catalyst.

Synthesis, complexation of 1,2,3-(NH)-triazolylferrocene derivatives and their catalytic effect on thermal decomposition of ammonium perchlorate

Some ferrocene derivatives like 2,4-dinitrophenylhydrazine derivative of acetyl ferrocene, 1-pyrrolidinylmethyl ferrocene, di-ter-butyl ferrocene and 1,3-diferrocenyl-l-butene (DFB) have been synthesised and characterised by infrared, nuclear magnetic resonance, ultraviolet, iron content, etc. To study the effect of their incorporation on performance, ammonium perchlorate/hydroxyl-terminated polybutadiene-based composite propellants containing these derivatives have been prepared and studied for burn rates, tensile strength and percentage elongation followed by their static test evaluation. A comparison of the properties of propellant containing solid and liquid ferrocene derivatives has been made with those containing Fe/sub 2/O/sub 3/ and n-butyl ferrocene, respectively. The data clearly indicates that these ferrocene derivatives are better than Fe/sub 2/O/sub 3/ and n-butyl errocene. Also, DFB is the best among these derivatives. Like composite propellants, DFB increases burn rate in fuel-rich propellants also.

http://publications.drdo.gov.in/ojs/index.php/dsj/article/download/3800/2187

S. K. Mane

Papers

Evaluation of Ferrocene Derivatives as Burn Rate Modifiers in AP/HTPB-Based Composite Propellants