Sign control of circularly polarized luminescence of chiral Schiff-base Zn(ii) complexes through coordination geometry changes

Abstract

The handedness of circularly polarized luminescence (CPL) of Zn(II) complexes with chiral Schiff-base ligand can be controlled by coordination geometry changes in solution and in the solid state. The relationships...

Circularly polarized blue fluorescence based on chiral heteroleptic six-coordinate bis-pyrazolonate-Zn2+ complexes

“…Both R, R-Zn 2+ and S,S-Zn 2+ display a large polarization degree, reaching −0.0065 for the R,R-configuration and +0.0068 for the S,Sconfiguration (see Fig. S8 †), which are at the top end of reported chiral organo-Zn 2+ complexes, [25][26][27][28][29][30][31][32][33][34][35][36] and are compar-…”

“…Dalton Transactions able to several chiral organo-Ln(III) complexes with magnetically allowed f-f transitions. 38,46,47 The observed g lum may benefit from two major factors: (i) direct participation of chiral 1,2-diamines rather than a twisted re-coordination with other organic ligands (for example, salicylaldehyde 29,31,34,48 and vanillin 33,49 ) that contributes to an enhanced chirality of the stereogenic centers localized at 1,2-diamine carbons (C3 and C4); (ii) the short spatial distance of the chiral carbon atom (C3 and C4) on the chiral 1,2-diamines from the coordination centre (Zn 2+ ion).…”

“…To date, despite the concerted efforts that have been made in the synthesis of CPL-active Zn 2+ complexes, [25][26][27][28][29][30][31][32] there are few examples of blue CPL systems based on chiral Zn 2+ complexes, [33][34][35][36] particularly systems that fully comply with the National Television Standards Committee (NTSC) standard blue light requirements (Commission Internationale de l'Eclairage (CIE) chromaticity coordinates; x = 0.14, y = 0.08). 37 We should note pioneering works by Tang, 33 Tsuno 34 and Gao 35 et al that have applied the chiral induction ability of chiral 1,2-diamines and their derivatives in the development of chiral homoleptic Schiff-base Zn 2+ complexes, which exhibit blue to yellowish green photoluminescence (λ PL ≥ 462 nm) with a Salen-induced moderate CPL performance (Φ PL ≤ 14.8%; |g lum | ≤ 3.2 × 10 −3 ). Bernhard and co-workers have reported a new class of chiral homoleptic 2,2′-bipyridyl Zn 2+ complexes 36 that generate close to ideal blue light, but with a relatively low CPL activity (|g lum | ≤ 2.4 × 10 −3 ) that may be due to the distance of the chiral pinene ring from the Zn 2+ ion.…”

Chiroptical Response Control of Planar and Axially Chiral Polymethylene-Vaulted Platinum(II) Complexes Bearing 1,1′-Binaphthyl Frameworks

“…Organometallic complexes with chiral ligands have attracted increasing attention in recent years as promising CPL materials owing to their large Stokes shifts and highly efficient phosphorescence properties, which are difficult to achieve using SOMs . Various examples of CPL-active organometallic complexes whose metal centers are Cr­(III), Zn(II), Cu­(I), Ru­(III), Re­(I), Pt­(II), Ir­(III), and Au­(I) have been used for developing efficient CPL emitters. However, despite several studies on the correlation between the structure and CPL properties in SOMs, ,,, a clear molecular design for achieving efficient CPL has not been established for organometallic complexes.…”

External environment sensitive circularly polarized luminescence properties of a chiral boron difluoride complex

“… 14 One of the strategy to achieve CPL control of SOMs is to design molecules that are sensitive to conformational changes in response to the external environment. To date, a variety of SOMs have been developed in which CPL properties can be controlled depending on the external environment, such as solvent, 15 dispersed matrix 16 and pH. 17 …”