title: Synthesis and characterisation of lanthanide-hydroporphyrin dyads.
abstract: Fluorescence spectroscopy is in many ways the ideal tool for the interrogation of complex biological systems, as it is non-invasive, sensitive, and offers high spatiotemporal resolution. For biomedical imaging luminescent probes absorbing and emitting in the red-to-near infrared (NIR) region are best suited to maximise tissue penetration and minimise damage to cellular components. NIR-emitting lanthanides (Ln) sensitised with red-absorbing antennae are promising candidates for these applications, assuming the challenges of poor photophysical properties and tedious syntheses of the complexes are overcome. Chlorins are porphyrin-type tetrapyrroles with intense red absorption. Recently chlorins have been shown to sensitise Yb and Nd emission when incorporated into Ln-complexes. Here we expand on our previous work, and explore the effect of chlorin structure, metallation state, chlorin-Ln-complex linker length and mode of attachment on the properties of chlorin-Ln complexes. As chlorin absorption bands are ∼20 nm fwhm and readily tunable, a deeper understanding of structure-property relationships would enable the use of chlorin-Ln complexes in multicolour imaging using antenna-specific excitation. A detailed description of antenna and complex syntheses and photophysical characterisation is given. A number of challenges were identified, which will have to be addressed in future studies to enable multicolour imaging using the NIR-emitting lanthanides.
authors.affiliation: Department of Chemistry - BMC, Uppsala University, 75123 Uppsala, Sweden. eszter.borbas@kemi.uu.se.
authors.forename: Ruisheng
authors.initials: R
authors.lastname: Xiong
authors.forename: Julien
authors.initials: J
authors.lastname: Andres
authors.forename: Kira
authors.initials: K
authors.lastname: Scheffler
authors.forename: K Eszter
authors.initials: KE
authors.lastname: Borbas
mesh_terms: D028581:Lanthanoid Series Elements / Q000737:chemistry*; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000737:chemistry*; D011166:Porphyrins / Q000737:chemistry*
chemical_list: D028581:Lanthanoid Series Elements; D009942:Organometallic Compounds; D011166:Porphyrins