Ligand-regulated three-photon AIE properties of manganese(II) complexes for photodynamic therapy.

Owing to the advantages of deeper penetration depth and lower biological damage, multi-photon AIE probes are widely used in the field of multi-photon therapy. We have developed a series of carbazole terpyridine manganese(II) complexes (MD1-MD3) that are promising as aggregation-induced emission (AIE) photosensitizers (PSs). MD1-MD3 exhibit excellent three-photon AIE properties in DMSO/H2O solution. We modulated the AIE properties of the Mn(II) complexes by introducing halogen atoms (Br/I). The three-photon fluorescence intensity of the complexes upon introducing halogen atoms is strong under the conditions of fw = 99% and 60%, respectively. Based on halogen-substituted carbazole ligands, MD3 can be applied as a multi-photon absorption photosensitizer which can produce 1O2 and O2˙-. MD3 damages the mitochondrial morphology, leads to a decrease in mitochondrial membrane potential, and then triggers the apoptosis of cancer cells. Furthermore, MD3 is successfully applied as a photosensitizer in tumor theranostics in vivo. This work provides a new idea for ligand modulation of multiphoton AIE ground state transition metal complexes to make them multiphoton therapeutic agents.

Multi-photon absorption organotin complex for bioimaging and promoting ROS generation.

Compared to general fluorescent dyes, multi-photon fluorescent dyes exhibit deeper tissue penetration and lower auto-fluorescence in the bio-imaging field. Therefore, it is necessary to develop an efficient multiphoton imaging agent for deep tissue imaging. In this work, an organotin derivative (HSnBu3) has been designed and synthesized, which shows multiphoton absorption activity. In constrast to the ignorable three-photon activity of the ligand, the complex (HSnBu3) exhibits three-photon activity under NIR excitation (1500 nm). Results of chemical and biological tests confirmed that HSnBu3 was more easily activated by oxygen resulting in a higher level of 1O2, which could induce a decrease in mitochondrial membrane potential in HepG2 cells. It suggests that HSnBu3 has potential in photodynamic therapy.

(3Z,5E)-2-Amino-4,6-bis(pyridin-3-yl)hepta-1,3,5-triene-1,1,3-tricarbo-nitrile.

In the title compound, C20H14N6, the dihedral angle between the pyridine rings is 37.98 (7)°. In the crystal, N-H⋯N hydrogen bonds link the mol-ecules into (10) sheets.