Molecular and Nanoaggregation in Cyclometalated Iridium(III) Complexes through Structural Modification

Abstract

New terpyridyl ligands TP1, TP2 and cyclometalated iridium(III) complexes 1 and 2 based on these ligands have been synthesized. The ligands and complexes have been characterized by elemental analysis and spectroscopic studies (ESI‐MS, 1H and 13C NMR, UV/Vis, fluorescence). The molecular structure of 1 has been verified by X‐ray single‐crystal analysis. It has been unambiguously established that variation of the substituents on 1 and 2 leads to molecular aggregation in 1, while 2 remains nonaggregated. Furthermore, complexes 1 and 2 have been successfully utilized as capping agents for the stabilization of gold nanoparticles (AuNPs). It is of note that 1 forms discretely, while 2 aggregates AuNPs through the assemblage of ultrasmall nanoparticles. It has been affirmed by 1H NMR titration studies that –NH groups from 1 and 2 are involved in the capping of AuNPs. The role of simple structural variations in directing molecular and nanoaggregation has been clearly established for the first time by spectroscopic (UV/Vis, fluorescence, 1H NMR titration) and morphological studies [SEM, TEM, EDX (energy‐dispersive X‐ray), DLS (dynamic light scattering)].

Anticancer Activity of Iridium(III) Complexes Based on a Pyrazole-Appended Quinoline-Based BODIPY

“…The N3–Ir1–N5, N6–Ir1–C44 and N7–Ir1–C42 bite angles in this complex are 74.3(3)°, 80.6(4)°, and 80.4(4)°, respectively. The N6 and N7 atoms from 2-phenylpyridine are trans-disposed, which is normal and similar to earlier reports. − The Ir1–C and Ir1–N bond distances [Ir–C, 2.00 Å; Ir–N, 2.04 Å] and C–Ir1–N, C–Ir1–C, and N–Ir1–N bond angles are regular and similar to other closely related cyclometalated iridium­(III) complexes. ,,,, On the other hand, Ir1 in complex 2 adopted the typical “piano-stool” geometry, wherein the metal center coordinated with the C 5 Me 5 ring in an η 5 -fashion, occupying three coordination sites. Other sites about the metal center are occupied by the N^N-chelating site of BODIPY via N3 and N5 atoms and a chloro group.…”

“…The N6 and N7 atoms from 2phenylpyridine are trans-disposed, which is normal and similar to earlier reports. 22,46,62,63,65 On the other hand, Ir1 in complex 2 adopted the typical "pianostool" geometry, wherein the metal center coordinated with the S1). The η 5 -C 5 Me 5 ring is symmetrically bonded to the metal center with an average Ir−C distance of 2.14 Å (range 2.12−2.16 Å).…”

Combined Experimental and Theoretical Studies on the Rubbing-Induced Fluorescence Behavior of a Luminophore in the Solid State

“…After 70% water in THF, quenching of fluorescence takes place ( Figure 1 ), which is also consistent with the absorption profiles of RIL in the THF/H 2 O medium ( Figure S6 ). From these spectral phenomena, it is articulated that here, the red shifting 34 (20 nm Stokes shift) is in agreement with the J-type aggregation toward AIE property 35 , 36 and the optimum level of aggregation with a higher emission intensity in solution betides at 70% water fraction.…”

Cyclometalated Ir(III) Complexes Involving Functionalized Terpyridine-Based Ligands Exhibiting Aggregation-Induced Emission and Their Potential Applications in CO2 Detection

“…Upon complexation with the metal center −NCH 3 protons shifted downfield and appeared at δ 3.91 and 3.46 ppm, respectively, for C2 and C3 , while aromatic protons due to C1 – C3 resonated in the range of δ 5.25–9.45 ppm. The occurrence and chemical shifts for various signals in the 1 H NMR spectra strongly suggested formation of the compounds Experimental Section) also corroborated well with formation of respective ligands ( TP1 – TP3 ) and complexes ( C1 – C3 ).…”