Bio-imaging with neutral luminescent Pt(ii) complexes showing metal⋯metal interactions

Abstract

Self-assembled platinum compounds resulting in stable, highly emissive and long-lived species are reported for cell imaging.

Recent Advances in Phosphorescent Pt(II) Complexes Featuring Metallophilic Interactions: Properties and Applications

“…102 In their paper, they were able to show that complex 22 (Chart 3) is readily internalized in living human cervical carcinoma (HeLa) cells and mostly accumulated into the nuclear region, as demonstrated by z-stack confocal microscopy and colocalization studies. Upon internalization, complex aggregation via establishment of metallophilic interactions induced a sizeable bathochromic shift of both absorption and emission MMLCT bands, which were efficiently used to shift the excitation wavelength down to exc = 543 nm (low-lying 1 MMLCT band), an unprecedented result for nonporphyrinic phosphorescent bioprobes (Figure 18).…”

TD-DFT Benchmark on Inorganic Pt(II) and Ir(III) Complexes

“…NLO, luminescence). [36][37][38][39][40][41][42][43][44][45][46][47][48] These considerations prompted us to start a comprehensive investigation with the aim of getting further insights into the spectroscopic behaviour of such compounds and of proposing reliable computational protocols, which could be profitably used also for other transition metal compounds. We have compared different functionals and basis sets trying to define the methods of choice by comparison to experimental results reported in previous investigations.…”

Neutral N^C^N terdentate luminescent Pt(ii) complexes: their synthesis, photophysical properties, and bio-imaging applications

“…In order to further investigate the photophysical properties of PtL 2 Cl and the possibility of establishing metallophilic Pt⋯Pt and π-π stacking interactions, with subsequent modulation of both excitation and emission properties, 19,20,27 aggregation studies were performed in an air-equilibrated dioxane-water mixture at different ratios ranging from pure dioxane to dioxane-water 1 : 4. During these experiments, the concentration of the amphiphilic complex PtL 2 Cl was kept constant (5 × 10…”

“…[15][16][17][18] Another fast emerging field regarding luminescent Pt(II) complexes is their application as luminescent labels for bioimaging. [19][20][21][22][23] Although fluorescent organic labels are still the leading choice for such applications, [24][25][26] phosphorescent Pt(II) complexes are slowly gaining attention and could outclass organic molecules. In fact, Pt complexes display many advantages such as: (i) a wide emission colour tunability by an adequate choice of the ligands; (ii) a better stability towards photo-and chemical degradation; (iii) a very large Stokes shift that allows the detection of their emission at a much lower energy than the excitation energy; (iv) long-lived luminescent excited states owing to their triplet-manifold nature; (v) emission lifetimes typically two to three orders of magnitude longer than those of classic organic fluorophores.…”

“…See DOI: 10.1039/c4dt03165b ‡ All these authors have contributed equally to this work. The investigation of platinum complexes for biological applications concerns mostly monomeric compounds, but aggregates show some important features as well: 19,20 (i) the emitter is shielded from the environment and in particular from dioxygen that could induce quenching; (ii) the rigidity, due to the packing of molecules in determined structures, decreases nonradiative processes; (iii) the reactivity or toxicity of the complexes is diminished by the difficult accessibility of the metal centre; (iv) changes in the excited state nature and properties lead to a bathochromic shift of excitation and emission towards more biologically interesting spectral windows and sometimes to an enhancement of the photophysical properties. In this respect, amongst all luminescent platinum derivatives, those bearing either an N^C^N 22,23 20,28,29 For this purpose, we decided to undertake a systematic study of the bio-imaging and cytotoxicity features of a series of platinum complexes bearing a N^C^N cyclometallated 1,3-di(2-pyridyl)-benzene by varying the molecular hydrophobic/hydrophilic ratio (through the introduction of ethyleneglycol moieties of different lengths) and the ancillary ligand, the incubating medium and the staining concentration.…”