FTIR sensing of inhomogeneous systems using immobilized organometalcarbonyl probe groups

Tricarbonyl(eta (5)-cyclohexadienyl)iron(0) and dicarbonyl(triphenylphosphi ne)(eta (5)-cyclo-hexadienyl)iron(0) were derivatized by attachment of an a minopropylsilyl link and covalently attached to fumed silica particles. The fumed silica was coated onto the ZnSe element of an attenuated total refle ction (ATR) cell for Fourier transform infrared (FTIR) spectroscopic analys is. The immobilized organometalcarbonyl probe groups are shown to retain th eir capacity to function as a key element of a molecular sensor assembly an d the nu (CO) bands of the two probe groups were interrogated to calibrate the responses for 0-5% levels of dodecane in cyclohexanol to within +/-0.1% . The potential for dual sensing is described and the simultaneous monitori ng of two discrete regions of a dynamically varying inhomogeneous system is reported for the determination of dodecane in cyclohexanol as solutions mi x across a permeable barrier in the ATR cell.