The encapsulation and/or surface modification can stabilize and protect the phosphorescence bio-probes but impede their intravenous delivery across biological barriers. Here, a new class of biocompatible rhenium (Re I ) diimine carbonyl complexes is developed, which can efficaciously permeate normal vessel walls and then functionalize the extravascular collagen matrixes as in situ oxygen sensor. Without protective agents, Re I -diimine complex already exhibits excellent emission yield (34%, 𝝀 em = 583 nm) and large two-photon absorption cross-sections (𝝈 2 = 300 GM @ 800 nm) in water (pH 7.4). After extravasation, remarkably, the collagen-bound probes further enhanced their excitation efficiency by increasing the deoxygenated lifetime from 4.0 to 7.5 μs, paving a way to visualize tumor hypoxia and tissue ischemia in vivo. The post-extravasation functionalization of extracellular matrixes demonstrates a new methodology for biomaterial-empowered phosphorescence sensing and imaging.
Metal ions (Ag+, Cd2+, Eu3+, Sm3+) and protons modulate the structural information of a pyrazine-based ligand, thus generating linear and bent conformations, associated to diprotonated forms, a polymeric architecture, rack-like complexes and a grid.
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