Synthesis, crystal structure, photoluminescence and theoretical studies of a series of copper(I) compounds based on imidazole derivatives

Synthesis, Structures, and Photophysical Properties of a Series of Rare Near-IR Emitting Copper(I) Complexes

“…Specifically, the strongly σ-donating PMe 3 ligands in 1a lead to a slightly larger P1–Cu–P2 angle of 117.06(2)°, while the tri­(aryl)­phosphines give smaller angles of only 115.70(3) and 115.16(5)° for 2a and 3a , respectively. Interestingly, the P1–Cu–P2 angles in the structurally related PPh 3 complexes A , B , E , F , I , J , and L are significantly larger with 123–131°. − The Cu–P bonds in 1a – 3a of 2.2313(6)–2.2497(13) Å are within the typical range found for these types of complexes. − We also note that the higher electron density at the copper­(I) center in 1a caused by the strong σ-donation of PMe 3 leads to longer Cu–N distances (2.089(2)/2.094(2) Å) compared to 2a and 3a (2.070(2)/2.091(2); 2.070(2)/2.089(3) Å).…”

“…We have reported on the synthesis and photophysical investigation of a series of trigonal NHC and tetrahedral phosphine copper­(I) compounds with 2-(2′-pyridine)­benzthiazol (pybt) or 2-(2′-quinoline)­benzthiazol (qybt) as π-chromophore ligands. The incorporation of the sulfur into the conjugated π-ligand system leads to red to near-IR emission of the Cu I complexes with maxima between λ max = 593–757 nm, while their nitrogen analogues exhibit green to orange emission. ,− Although the luminescence is weak in solution, it becomes unusually intense for near-IR emitting Cu I complexes, which are very rare, reaching quantum yields of up to Ω = 0.11 and lifetimes of several microseconds in the solid state. Our low-temperature measurements show an increase in lifetime and a bathochromic shift of the emission of the phosphine complexes at 77 K compared to room temperature with λ max ranging from 639 to 812 nm, but no clear evidence for TADF could be obtained, leaving us to assign the emission to originate from a 3 (Cu→pybt/qybt)­MLCT state, which is supported by our DFT and TD-DFT studies.…”

“…Our strategy is inspired by the observation that incorporation of heavier analogues of light main-group elements, such as nitrogen or oxygen, can lead to excited states, which are much lower in energy. This has been shown for siloles, phospholes, and thiophenes, contrasting significantly the higher-energy emission of their carbon, nitrogen, or oxygen congeners. − Copper­(I) complexes of 2-(2′-pyridine)­imidazole-type ligands are well-known to emit in the green to orange region of the electromagnetic spectrum (Chart ), ,− and we have thus chosen those for replacement of one nitrogen for sulfur, expecting low-energy emission in the red to NIR region. Furthermore, we modified the conjugation of the chromophore ligand to further control the excited-state energy.…”

Cyclic (Amino)(aryl)carbenes Enter the Field of Chromophore Ligands: Expanded π System Leads to Unusually Deep Red Emitting CuI Compounds

“…However, one of the remaining challenges is to achieve efficient triplet-state emission in the deep red to near (N)­IR region of the electromagnetic spectrum because of its great importance for the development of night vision displays, bioimaging agents, and optical-based telecommunication. − The problem at such low emission energies is the fairly large vibrational overlap between the excited state and the ground state, leading to efficient nonradiative decay within the frame of the energy gap law for nested states and the lower k r compared to high-energy emission in general. − As part of our project to investigate new design criteria for Cu I NIR emitters, we recently reported trigonal N-heterocyclic carbene (NHC) and tetrahedral phosphine copper­(I) compounds with 2-(2′-pyridine)-benzothiazole or 2-(2′-quinoline)­benzothiazole as π chromophore ligands. In comparison to their nitrogen analogues, − incorporation of sulfur into the π chromophore lowers the π* orbital, and consequently, the emission is shifted from green or orange to the red or even NIR with Φ up to 0.11 in the solid state, but relatively small k r values were obtained …”

Synthesis and Characterization of some Transition Metals Complexes with new Ligand Azo Imidazole Derivative

“…The ligand metal complexes in electronic spectra were measured in dimethyl form (DMSO) as a solvent at the range (200-800)nm. [MnL(H2O)Cl2]H2O (1): The electronic spectrum of Mn(II) complex showed absorption bands at (16891, 27173) cm -1 due to the transitions 6 A1g→ 4 T1g(G) , 6 A1g→ 4 T2g(D), respectively, indicating octahedral geometry [27]. The measured magnetic moment µeff.…”