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The donor-π-acceptor ferrocene conjugated malononitrile dimer [C5H5–Fe–C5H4–C(H) C(CN)–C(NH2) = C(CN)2] (1) has been synthesized and characterized with the aid of analytical and spectroscopic techniques [FT-IR, GC-Mass, 1H and 13C NMR]. The thermal stability of the compound 1 was investigated using thermogravimetric analysis (TGA) and differential thermal analysis (DTA), exhibit the compound is stable up to 180 °C. The photophysical properties were performed by UV–visible and fluorescence spectroscopic methods and the compound 1 exhibited weak fluorescence emission. In addition, the optical band gap (Eg) was calculated using diffused reflectance spectroscopic technique which shows the band gap value of Eg = 3.6 eV. The redox wave of the compound 1 was determined by cyclic voltammetry, revealed that one electron transfer ability of the ferrocene to ferrocenium ion. The experimentally observed HOMO and LUMO values are good agreement with the theoretical calculation by DFT-M06 method using 6–31 + G** as basis set. The solvatochromic studies of compound 1 shows negative solvatochromism due to the high ground state polarizability in presence of cyano acceptors. Further, the nonlinear optical properties were investigated by Q-switched Nd-YAG laser and second harmonic generation efficiency (SHG) using para-nitroaniline (p-NA) as a standard and the results of SHG efficiency is 0.35 times comparable with p-NA.

Rickettsial diseases are caused by arthropod-borne obligate intracellular parasites. One such rickettsial infection is scrub typhus, which is an important cause of fever of unknown origin. Spectrum of presentation is variable. There are reports of scrub typhus with CNS complication, like meningoencephalitis, in adolescents and adults from various parts of India but not from Delhi. There are recent case reports of scrub typhus without CNS involvement in adults from Delhi. Its occurrence in the form of hemorrhagic fever with meningoencephalitis is rarer in children and is not so far reported from the state of Delhi. We present a case of a 4-year-old child from Delhi presenting with hepatosplenomegaly, thrombocytopenia, and altered sensorium, whose timely diagnosis and management saved her life, and this brings to our notice the emergence of scrub encephalitis in children.