Naphthalimide Phosphorescence Finally Exposed in a Platinum(II) Diimine Complex

Abstract

Room temperature (RT) phosphorescence is observed from a naphthalimide species for the first time in the square-planar chromophore Pt(dbbpy)(C[triple bond]C-NI)(2), where NI = N-butyl-4-ethynylnaphthalimide and dbbpy = 4,4'-di-tert-butyl-2,2'-bipyridine. The combination of static and time-resolved absorption and photoluminescence data is uniformly consistent with triplet-state photophysics localized on an appended C[triple bond]C-NI unit following excitation into the low-energy absorption bands. This molecule features rather impressive long-lifetime, high-quantum-efficiency NI-based RT phosphorescence (tau = 124 micros; Phi = 0.215) centered at 621 nm, exemplifying how the platinum acetylide linkage strongly promotes intersystem crossing in the NI subunit, representative of a class of molecules whose excited states are typically dominated by singlet fluorescence.

Room‐Temperature Long‐Lived 3IL Excited State of Rhodamine in an NN PtII Bis(acetylide) Complex with Intense Visible‐Light Absorption

“…[28] This is also different from our previous Pt II bis(acetylide) complexes with NI and NDI chromophores. [10,15,29] We therefore propose that the π-conjugated core of Rho-CϵCH is not directly coupled to the Pt II centre. Thus, interaction of the excited states is possible between the Pt II coordination centre and the Rho-CϵCH ligand.…”

“…[10,14,15,29] These complexes, however, suffer from either short absorption wavelengths or short T 1 lifetimes. [15] Considering the large numbers of organic chromophores, much room is left for exploring different organic chromophores to prepare Pt II bis(acetylide) complexes that show intense absorption in the visible region and to access the long-lived 3 IL triplet excited state.…”

“…[30][31][32][33][34][35][36][37][38] To the best of our knowledge, the studies of its triplet excited state and its application as a light-harvesting moiety in transition-metal complexes have never been reported. In our continuous attempts to access the long-lived 3 IL excited state of organic chromophores in transition-metal complexes, [8][9][10][13][14][15]29] we herein report on the incorporation of the rhodamine chromophore into a transition-metal complex to access the rhodamine-localised long-lived 3 IL excited state (Pt-Rho, Scheme 1). Our strategy was to use the aforementioned versatile N ∧ N Pt II bis(acetylide) scaffold to attach the acetylide rhodamine chromophore.…”

Long-lifetime reverse saturable absorption in a bipyridyl platinum(II) complex bearing naphthalimidylethynyl-substituted fluorenylacetylide ligands

“…1. Our choice of the C"CANI group to replace the BTZ group was motivated by reports of an extremely long-lived naphthalimidebased triplet excited state in a platinum diimine complex with C"CANI ligands [18].…”

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

“…Typically, the 3 IL state has a longer lifetime than the 3 MLCT state. [31][32][33] To assign the T 1 state of complex Pt-1 from the perspective of molecular orbitals, the UV/Vis absorption and the phosphorescence of the complexes were studied by time-dependent DFT (TDDFT) analysis. The calculated absorption bands of complex Pt-1 were at 570 nm and 429 nm (Table 2); these values were in good agreement with the experimental values (Table 1 and Figure 1).…”