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Herein a ratiometric fluorescent Cu(2+) probe was rationally constructed in a straightforward manner with the concept of aldehyde group protection/deprotection. The probe showed a ratiometric fluorescent response to Cu(2+) with a large emission wavelength shift (>100 nm) and displayed high selectivity for Cu(2+) over other metal ions due to distinct deprotection conditions. In addition, a Cu(2+)-promoted dethioacetalization mechanism was proposed.

Bis(coumarinyl) Schiff base 1 was designed and synthesized as a fluorescence turn‐on chemodosimeter for Fe3+. The chemodosimeter was readily synthesized in four steps from 2,4‐dihydroxybenzaldehyde. The addition of Fe3+ to chemodosimeter 1 induced about a 140‐fold enhancement influorescence. Furthermore, chemodosimeter 1 was also highly selective to Fe3+ over other metal ions, and most of the related metals ions exhibited negligible detection interference.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

Probe 1 has been synthesized as the first ratiometric fluorescent cobalt probe, and it exhibits several highly favorable features, in particular a remarkable ratiometric fluorescence response at two wavelengths. Importantly, the electronic energy transfer (EET) efficiency of the probe is modulated by the energy acceptor molar absorptivity variations on cobalt binding, which then transforms to a large ratiometric fluorescence response at two wavelengths. This signaling mechanism should open a new avenue for the development of powerful ratiometric probes with large emission signal ratios at two wavelengths for exciting applications in many fields.

A novel palladium-catalyzed CO-gas- and autoclave-free protocol for the synthesis of 11H-pyrido[2,1-b]quinazolin-11-ones has been developed. Quinazolinones, which are omnipresent motif in many pharmaceuticals and agrochemicals, were prepared in good yields by C-H bond activation and annulation using DMF as the CO surrogate. A (13) CO-labelled DMF control experiment demonstrated that CO gas was released from the carbonyl of DMF with acid as the promotor. The kinetic isotope effect (KIE) value indicated that the C-H activation step may not be involved in the rate-determining step. This methodology is operationally simple and showed a broad substrate scope with good to excellent yields.