Aromatic conjugation at the [β] position is an efficient strategy to construct NIR BODIPY dyes; functionalization of such BODIPYs is difficult because of fewer modifiable positions. The methyl group at the 3,5-position can be versatilely functionalized by the Knoevenagel condensation reaction. In this paper, a small series of non-symmetric thieno[3,2-b]thiophene-fused BODIPYs have been prepared via the condensation of 7H-thieno[2′,3′:4,5]thieno[3,2-b]pyrrole-6-carbaldehydes and various pyrroles, followed by coordination with BF₂. The resulting BODIPY dyes exhibited red absorption and emission with extremely high absorption coefficients (2 × 10⁵ M⁻¹ cm⁻¹) and fluorescence quantum yields up to 1.00. Importantly, the remaining methyl group at the 3-position can be further functionalized to achieve NIR probes; we then synthesized an organosilicon-based probe for F⁻ and evaluated its imaging in living cells. The structure–property relationships were interpreted on the basis of X-ray crystallography, optical spectroscopy and theoretical calculations.

Deprotonation of the bis(imidazolium) salt (1,1′-dimethyl-3,3′-ethylenediimidazolium dibromide, L·2HBr) with silver oxide in a solution mixture of CH₂Cl₂ and CH₃OH affords a silver carbene complex [Ag₂L₂]Cl₂ (1, L = 1,1′-dimethyl-3,3′-ethylenediimidazol-2-ylidene). With CH₃OH as the only solvent for the synthesis and after recrystallization in a chlorinated solvent in ambient condition, a polymeric silver complex [(L·2H)(Ag₂Br₄)]_n (2) was formed. The presence of chloride in complex 1 and bromide in complex 2 indicates that a halogen exchange reaction occurred unambiguously during the synthesis and not during recrystallization. The silver-carbene complex 1 undergoes a facile reaction with [(p-cymene)RuCl₂]₂ and (p-cymene)Ru[S₂C₂(B₁₀H₁₀)] to yield the binuclear complexes [(p-cymene)RuCl₂]₂L (3) and {(p-cymene)Ru[S₂C₂(B₁₀H₁₀)]}₂L (4). The latter compound contains a carbene ligand and a 1,2-dicarba-closo-dodecaborane ligand. Molecular structures of complexes 1–4 were confirmed by X-ray single-crystal analyses.