The 3D [(Cu₂Br₂){μ-EtS(CH₂)₄SEt}]_n material: a rare example of a coordination polymer exhibiting triplet–triplet annihilation

Abstract

EtS(CH)SEt, L1, forms with CuI a luminescent 2D polymer [CuI{μ-L1}] (CP1), which exhibits no triplet excitation energy migration, but with CuBr, it forms a 3D material (CP2), [(CuBr){μ-L1}] consisting of parallel (CuBrS) layers bridged by L1's. CP2 shows T-T annihilation at 298 K but not at 77 K.

From Short-Bite Ligand Assembled Ribbons to Nanosized Networks in Cu(I) Coordination Polymers Built Upon Bis(benzylthio)alkanes (BzS(CH2)nSBz; n = 1–9)

“…Alternatively, the use of ligand RS-(CH 2 ) m -SR with sterically less demanding substituents at the S-atom such as SMe or SEt, combined with long spacer units ( m = 6–9) will certainly also impact the architecture and porosity of the networks leading to MOF-like structures incorporating voids allowing guest molecules to be included. This hypothesis has been recently corroborated by the observation that complexation of CuBr and CuCl with EtS-(CH 2 ) 4 -SEt yields 3D networks [Cu 2 X 2 (EtS­(CH 2 ) 4 SEt) 4 ] n whose unusual Cu ← S → Cu bonding mode allows abnormal triplet energy migration processes. , So one may expect that also longer-chain EtS-(CH 2 ) m -SEt derivatives ( m = 6–9) may allow the crystallogenesis of more porous CuX networks, in which the S-atoms act as four-electron donors instead of the more common two-electron donor bonding mode.…”

“…These species exhibit generally intense and structureless bands spreading from 430 to 730 nm at room temperature. ,,− ,,,,− The photophysical characterization of the thioether-containing cubanes and related species included in 0D–3D materials was extracted from more focused studies from the literature, and includes the emission lifetimes (τ e ) at 298 and 77 K, which generally range from 0.2 to 16 μs. A table containing these reported photophysical data is provided in Table S7. ,,,− ,,,,,,,, The cubane-containing CPs in this series make no exception (Figure ) with the small difference that some bands expand beyond 700 nm (near-IR).…”

“…A table containing these reported photophysical data is provided in Table S7. 32,34,61,[85][86][87][88][89][90]35,36,42,44,46,48,53,59 The cubane-containing CPs in this series make no exception (Figure 29) with the small difference that some bands expand beyond 700 nm (near-IR). CP4, CP8, CP11, CP15, CP19, and CP23 exhibit τ e 's values in the predicted range (Table 2; 1.8 ≤ τ e ≤ 15 μs).…”

“…Decisive factors for this structural Noteworthy, no bonding of the sulfur atoms through the two lone pairs (i.e., a S-atom acting as a 4-electron donor) was observed, although such a Cu ← S → Cu mode is conceivable since it has been reported before for 3D-[(Cu 2 X 2 ){μ-EtS-(CH 2 ) 4 SEt}] n (X = Cl, Br). 85 Surprisingly, no solvent molecules are hosted within the cavities of the nanosized grid-shaped 2D sheets (for CH 2 = 6−9) 37 nor placed between the 2D-layers, and no entanglement of the networks occurs despite the occurrences for other dithioether-CuX CPs. 26,28,67,94−96 Statistically, the size of the SBUs is dominated by the planar Cu(μ 2 -X) 2 Cu rhomboid with Cu•••Cu distances from 2.6867(6) to 3.092(4)Å (18 examples).…”

“…This hypothesis has been recently corroborated by the observation that complexation of CuBr and CuCl with EtS-(CH 2 ) 4 -SEt yields 3D networks [Cu 2 X 2 (EtS(CH 2 ) 4 SEt) 4 ] n whose unusual Cu ← S → Cu bonding mode allows abnormal triplet energy migration processes. 58,85 So one may expect that also longer-chain EtS-(CH 2 ) m -SEt derivatives (m = 6−9) may allow the crystallogenesis of more porous CuX networks, in which the S-atoms act as four-electron donors instead of the more common twoelectron donor bonding mode.…”