Enhanced detection of explosives by turn-on resonance Raman upon host-guest complexation in solution and the solid state.

The recognition of nitroaromatic explosives by a tetrakis-tetrathiafulvalene-calix[4]pyrrole receptor (TTF-C[4]P) yields a "turn on" and fingerprinting response in the resonance Raman scattering observed in solution and the solid state. Intensity changes in nitro vibrations with analyte complexation occur via a mechanism of resonance between the 785 nm laser line and the strongly absorbing charge-transfer chromophore arising from the complex between electron-donating TTF-C[4]P and electron-accepting nitroaromatic explosives. The addition of chloride forms the Cl-·TTF-C[4]P complex resetting the system for reuse.

Ionic manipulation of charge-transfer and photodynamics of [60]fullerene confined in pyrrolo-tetrathiafulvalene cage.

A cage molecule incorporating three electron donating monopyrrolotetrathiafulvalene units was synthesised to host electron accepting [60]fullerenes. Formation of a strong 1 : 1 donor-acceptor (D-A) complex C60⊂1 was confirmed by solid state X-ray analysis as well as 1H NMR and absorption spectroscopic analyses of the arising charge-transfer (CT) band (λ = 735 nm, ε ≈ 840 M-1 cm-1). Inserting Li+ inside the [60]fullerene increased the binding 28-fold (Ka = 3.7 × 106 M-1) and a large bathochromic shift of the CT band to the near infrared (NIR) region (λ = 1104 nm, ε ≈ 4800 M-1 cm-1) was observed.