Boron Dipyrromethene (Bodipy) Phosphorescence Revealed in [Ir(ppy)₂(bpy-C≡C-Bodipy)]⁺

Abstract

The synthesis, structural characterization, electrochemistry, and molecular photophysics of [Ir(ppy)(2)(bpy-C[triple bond]C-Bodipy)](PF(6)), where ppy is 2-phenylpyridine and bpy-C[triple bond]C-Bodipy is 5-ethynyl-2,2'-bipyridine-8-phenyl-1,3,5,7-tetramethyl-4,4-bis(2,5-dioxaoct-7-ynyl)-4-bora-3a,4a-diaza-s-indacene (4), is presented. Static and dynamic photoluminescence and absorption measurements in conjunction with cyclic voltammetry were employed to elucidate the nature of the intramolecular energy transfer processes occurring in the excited state of the title chromophore. Parallel studies were performed on appropriate model chromophores (2 and 3) intended to represent the photophysics of the isolated molecular subunits, that is, triplet metal-to-ligand-charge-transfer ((3)MLCT) and triplet Bodipy intraligand ((3)IL) excited states, respectively. Upon charge transfer excitation of the title chromophore, the (3)MLCT based phosphorescence readily observed in 2 (Phi(em) = 0.027, tau = 243 ns) is quantitatively quenched resulting from production of the (3)Bodipy excited state through intramolecular triplet-triplet energy transfer. The formation of the (3)Bodipy-localized excited state is confirmed by features in the transient absorption difference spectrum, extended excited-state lifetime (tau = 25 micros), as well the observation of (3)IL Bodipy-based phosphorescence detected at 730 nm at 77 K. The low temperature Bodipy phosphorescence is readily produced in 4 as a result of the internal Ir(III) heavy atom.

Long‐Lived Room‐Temperature Near‐IR Phosphorescence of BODIPY in a Visible‐Light‐Harvesting N^C^N PtII–Acetylide Complex with a Directly Metalated BODIPY Chromophore

“…None of the previously reported BODIPY-containing Pt II and Ir III complexes showed RT phosphorescence. [18,22] One of those complexes showed phosphorescence of the BODIPY chromophore at 77 K (l em = 730 nm), [22] which supports our assignment of the RT emission of complex Pt-1 at 770 nm as the 3 IL emission of the BODIPY ligand.…”

“…Keywords: BODIPY · chromophores · phosphorescence · photochemistry · platinum py). [22] Thus, in all of these reported BODIPY dyads, the RT phosphorescence of BODIPY was never observed and the T 1 excited-state lifetime was usually not very long.…”

“…[21,22] On the other hand, BODIPY is a particularly interesting chromophore, [23,24] and has been incorporated into Pt II , Ru II , and Ir III complexes to afford visible-light harvesting and long-lived T 1 excited states. [18,22,25] However, the photophysical property of the components often collapse in the dyad. For example, for a BODIPY-containing Ru II complex, the intrinsic metal-to-ligand charge-transfer ( 3 MLCT) emission of the Ru II coordination center was quenched and no longlived triplet excited state was observed at room temperature (RT).…”

“…This lifetime is the longest RT triplet excited-state lifetime ever reported for BODIPY. The previous values for BODIPY-localized 3 IL states were 8-30 ms. [18,22,25,30] DFT calculations for assignment of the T 1 excited state: To confirm the 3 IL nature of the T 1 state of complex Pt-1, the spin-density surfaces of complexes Pt-1 and Pt-2 were analyzed ( Figure 5). [19] For complex Pt-2, the spin density was distributed on the Pt II center and on the N^C^N ligand; thus, the T 1 state of complex Pt-2 could be safely assigned as a 3 MLCT.…”

Synthesis of an E-BODIPY based fluorescent Co-polymer containing organoboron quinolate units

“…Its derivatives have found widespread application in modern science and medicine [10][11][12][13]. BODIPY derivatives have been used as acceptors and donors in energy transfer systems [10,[14][15][16][17][18][19]. These systems have potential applications in dyesensitized solar cells [20,21], chemical sensors [22,23] and photodynamic therapy [24][25][26].…”