Tuning peripheral π-stacking motifs in {Cr(tpy)2}3+ domains (tpy=2,2′:6′,2″-terpyridine)

Abstract

The homoleptic complexes [Cr (1) spectroscopic data were consistent with those reported [17]. A convenient route to homoleptic {Cr(4'-Xtpy) 2 } 3+ or heteroleptic {Cr(4'-Xtpy)(4'-Ytpy)} 3+ complexes uses a stepwise approach starting with the reaction of one equivalent of a tpy ligand with

Beyond Chiral Organic (p-Block) Chromophores for Circularly Polarized Luminescence: The Success of d-Block and f-Block Chiral Complexes

“…While the two former ions are known to be non-emissive, Cr III complexes are known to show NIR emission in the 600–800 nm region, arising from the two low-lying Cr III ( 2 E) and Cr III ( 2 T 1 ) spin–flip excited states ( Figure 13 ) (Jamieson et al, 1981 ; Kirk, 1981 , 1999 ; Forster, 1990 , 2002 ; Buldt and Wenger, 2017 ; Otto et al, 2018 ). In fact, Cr III complexes have long been known to exhibit interesting photophysical and photochemical properties as illustrated by the archetypal ter-bidentate [Cr(phen) 3 ] 3+ (Serpone et al, 1979 ; Ryu and Endicott, 1988 ; Isaacs et al, 2006 ; Donnay et al, 2007 ; Vandiver et al, 2010 ; Vasudevan et al, 2010 ; Doistau et al, 2018 , 2020 ), bis-terdentate [Cr(tpy) 2 ] 3+ (Serpone et al, 1979 ; Scarborough et al, 2012 ; Constable et al, 2014 ; Schönle et al, 2015a , b ; Barbour et al, 2017 ), and analogs (Zare et al, 2017b ; Jiménez et al, 2018 ). In all cases, the ligand-field strength induced by the phen and tpy ligands is strong enough to induce near-infrared phosphorescence arising from the lowest-lying Cr( 2 T 1 ) and Cr( 2 E) excited states, but the associated very low quantum yields (<0.2%) are strong limitations for their use as CPL probes.…”

CrIIIas an alternative to RuIIin metallo-supramolecular chemistry

“…Creutz-Taube complex, (b) [(tpy)Ru(L)Ru(tpy)] m+ complexes, [69][70][71] (c) [(tpy)Ru II (L)Co III (tpy)] 5+ complexes displaying directional electron transfer, 72,73 (d) [(tpy)Ru II (L)Os II (tpy)] 4+ complexes displaying directional energy transfer. 74,75 six-coordinate bis-terimine 83,84 and ter-bisimine 46,81,82 Cr III complexes. Building on the identification of labile Cr III -O(triflate) bonds and their easy formation from Cr-Cl bonds, we herein propose to extend this procedure for the synthesis of a series of novel back-to-back dinuclear [X 3 Cr III (L)Cr III X 3 ] complexes (Scheme 1, X 3 = Cl 3 or X 3 = tpy), which are reminiscent of the well-known Ru II dyads.…”

“…However, the lack of easy accessible synthetic procedures for the preparation and characterization of pure heteroleptic polynuclear chromium complexes has up to now prevented Cr III polypyridines from being used as active building blocks in (supra)molecular optical devices. Recently, Barker et al, 81 Isaacs et al 82 and Housecroft and Constable et al 46,83,84 tried to find a remedy for this frustrating limitation with the systematic exploration of the stability and lability of mononuclear 59,60 The upward green arrow stands for the lowest-energy spin-allowed absorption transition, while the downward red arrow refers to the lowest-energy phosphorescence.…”

Reversible four-color electrochromism triggered by the electrochemical multi-step redox of Cr-based metallo-supramolecular polymers

“…15 The results indicated that the oxidation state of the Cr ions of polyCr was trivalent. From the extended X-ray absorption ne structure (EXAFS) region, the tting by using crystal structure of reported Cr complex 16 (Fig. 2b) revealed that the coordination lengths around the Cr ions Cr-N were 2.020 A and 2.208 A (R-factor; 1.37%, Table 1, EXAFS oscillation is shown in Fig.…”