ic7b01942_si_001.pdf (2.03 MB)
Platinum Complexes of N,N′,N″,N‴‑Diboronazophenines
journal contribution
posted on 2017-10-12, 11:36 authored by Hu Lei, Shawkat M. Aly, Paul-Ludovic Karsenti, Daniel Fortin, Pierre D. HarveyAzophenine,
(α-C6H5NH)2(C6H5–NC6H2N–C6H5), well known to be non-emissive, was rigidified
by replacing two amine protons by two difluoroboranes (BF2+) and further functionalized at the para-positions of the phenyl groups by luminescent trans-ArCC–Pt(PR3)2-CC ([Pt]) arms [Ar = C6H4 (R = Et), hexa(n-hexyl)truxene) (Tru; R = Bu)]. Two effects
are reported. First, the linking of these [Pt] arms with
the central azophenine (C6H4–NC6H2(NH)2N–C6H4; Q) generates very low energy charge-transfer
(CT) singlet and triplet excited states (3,1([Pt]-to-Q)*) with absorption bands extending all the way
to 800 nm. Second, the rigidification of azophenine by the incorporation
of BF2+ units renders the low-lying CT singlet
state clearly emissive at 298 and 77 K in the near-IR region. DFT
computations place the triplet emission in the 1200–1400 nm
range, but no phosphorescence was detected. The photophysical properties
are investigated, and circumstantial evidence for slow triplet energy
transfers, 3Tru* → Q,
is provided.