MagnetoPlasmonic Waves/HOMO-LUMO Free π-Electron Transitions Coupling in Organic Macrocycles and Their Effect in Sensing Applications

Abstract

Optical and magneto-optical surface plasmon resonance (MOSPR) characterization and preliminary sensing test onto single- and multi-layers of two organic macrocycles have been performed; TbPc2(OC11H21)8 phthalocyanine and CoCoPo2 porphyrin were deposited by the Langmuir-Schäfer (LS) technique onto proper Au/Co/Au magneto-optical transducers. Investigations of the MOSPR properties in Kretschmann configuration by angular modulation, gives us an indication about the potential discrimination of two organic macrocycles with absorption electronic transition in and out of the propagating plasmon energy spectral range. An improved molecular vapors sensitivity increase by the MOSPR sensing probe can be demonstrated depending on the overlap between the plasmonic probe energy and the absorption electronic transitions of the macrocycles under investigation. If the interaction between the plasmon energy and molecular HOMO-LUMO transition is preserved, a variation in the complex refractive index takes place. Under this condition, the magneto-plasmonic effect reported as 1/|MOSPR| signal allows us to increase the detection of molecules deposited onto the plasmonic transducer and their gas sensing capacity. The detection mechanism appears strongly enhanced if the Plasmon Wave/HOMO-LUMO transitions energy are in resonance. Under coupling conditions, a different volatile organic compounds (VOC) sensing capability has been demonstrated using n-butylamine as the trial molecule.

Phthalocyanine and Porphyrin Derivatives and Their Hybrid Materials in Optical Sensors Based on the Phenomenon of Surface Plasmon Resonance

“…The authors of [21,58] used this technique for monitoring optical and morphological changes in the LS layers of Zn(II) and Co(II) porphyrins upon their interaction with VOCs and amines. Films of ethane-bridged zinc bis-porphyrin (ZnPP with R = -CH 2 CH 3 , Figure 10) were deposited by the horizontal lifting or LS technique onto magnetoplasmonic substrates.…”

“…The same group of authors [58] compared the MOSPR sensor response of CoPP (Figure 10) and bisphthalocyanine of terbium Tb(Pc(OC 11 H 21 ) 4 ) 2 . To prepare a MOSPR sensor for the detection of n-butylamine, their films were deposited by the LS method onto Au/Co/Au magneto-optical transducers.…”