A series of σ-SiH copper complexes with different carbazole derivatives have been synthesized and characterized that adopt a neutral Si H P 2 ligand (Si H P 2 = (2-i Pr 2 PC 6 H 4 ) 2 Si H Me) and present photophysical properties. A previously reported copper complex (Si H P 2 )Cu(carbazolide), and its derivatives showed that tuning of the emission properties is possible by incorporating various substituents on the carbazolide moiety. Newly synthesized copper complexes (2−6) having 3,6-dichlorocarbazolide, 3,6dibromocarbazolide, 1-fluorocarbazolide, 3,6-dimethylcarbazolide, and 3,6diphenylcarbazolide show a range of λ max values of emission from 418 to 511 nm. Detailed analysis supports that their emission bands originate from excited states with Cu metal−ligand charge transfer (MLCT) and/or ligand-centered (LC) π−π* transitions. Substitution of a methyl or trifluoromethyl group at the 1-position of the carbazolide moiety was also investigated to regulate the structural tuning of the copper emitters. From the X-ray crystallographic data of (Si H P 2 )Cu(1-methylcarbazolide) ( 7) and (Si H P 2 )Cu(1,3-di(trifluoromethyl)carbazolide) (8), unusual structural features, arising from the interaction of a SiH moiety with CH 3 and CF 3 , respectively, were recognized. Such interaction forces the carbazolide moiety to tilt, while the copper geometry remains consistent with the other complexes. In the case of 8, a SiH•••F 3 C interaction locks the carbazolide moiety in place, restricting its orbital overlapping with a copper-based orbital, according to the theoretical analysis by using density functional theory (DFT) computations. Thus, the unusual tilting results in deep-blue emission with a λ max of 430 nm.

Gold-centered carbene–metal–amides (CMAs) containing cyclic (alkyl)(amino)carbenes (CAACs) are promising emitters for thermally activated delayed fluorescence (TADF). Aiming at the design and optimization of new TADF emitters, we report a density functional theory study of over 60 CMAs with various CAAC ligands, systematically evaluating computed parameters in relation to photoluminescence properties. The CMA structures were primarily selected based on experimental synthesis prospects. We demonstrate that TADF efficiency of the CMA materials originates from a compromise between oscillator strength coefficients and exchange energy (ΔEST). The latter is governed by the overlap of HOMO and LUMO orbitals, where HOMO is localized on the amide and LUMO over the Au–carbene bond. The S0 ground and excited T1 states of the CMAs adopt approximately coplanar geometry of carbene and amide ligands, but rotate perpendicular in the excited S1 states, resulting in degeneracy or near-degeneracy of S1 and T1, accompanied by a decrease in the S1-S0 oscillator strength from its maximum at coplanar geometries to near zero at rotated geometries. Based on the computations, promising new TADF emitters are proposed and synthesized. Bright CMA complex (Et2CAAC)Au(carbazolide) is obtained and fully characterized in order to demonstrate that excellent stability and high radiative rates up to 106 s−1 can be obtained for the gold–CMA complexes with small CAAC–carbene ligands.

The synthesis and characterization of a series of nickel complexes bearing a bismuth-containing pincer ligand are presented herein. In particular, synthesis of a 4-coordinate Bi–Ni(II) complex allows the influence of bismuth on a d8 Ni(II) ion to be investigated. A trigonal-bipyramidal complex, (BiP2)Ni(PPh) (1), possessing an anionic bismuth donor was prepared via the Bi–C bond cleavage of a BiP3 ligand (BiP3 = Bi(o-P i Pr2-C6H4)3) mediated by Ni(0). To remove a PPh moiety, compound 1 was treated with MeI to give a 5-coordinate nickel(II) complex (MeBiP2)Ni(PPh)(I) (2), followed by its exposure to heat or UV irradiation, resulting in the formation of a nickel halide complex, (BiP2)Ni(I) (3). The X-ray crystal structure of 2 revealed that the methyl moiety binds to a bismuth site, providing a neutral MeBiP2 ligand, while the iodide anion is bound to the nickel(II) center, displacing one phosphine donor. Because of the methylation on a Bi site, the Bi–Ni bond in 2 is clearly elongated relative to that of 1, which indicates that the bonding interactions between Bi and Ni are substantially different. Interestingly, compound 3 revealing a sawhorse geometry is significantly distorted away from a square-planar structure compared to the previously reported nickel(II) pincer complexes, (NP2)Ni(Cl) and (PP2)Ni(I). Such difference indicates that a bismuth donor can be a structurally influencing cooperative site for a nickel(II) ion, leading to have a Ni(I)–Bi(II) character. Migratory insertion of CO into a Ni–C bond of 1 gives (BiP2)Ni(COPPh) (4), which further leads to an analogous methylated product (MeBiP2)Ni(COPPh)(I) (5) from reaction with MeI. Due to the structural influence of a carbonyl group in each step, the total reaction time from 1 to 3 was dramatically reduced. The bimetallic cooperativity of the complexes and unusual bonding properties presented here highlight the potential of a bismuth–nickel moiety as a new type of heterobimetallic site for the design of bimetallic complexes to facilitate a variety of chemical transformations.

Soft grippers based on stimuli‐responsive materials show great promise to perform safe interaction and adaptive functions in unstructured environments. Hence, improving flexibility and designability of the stimuli‐responsive soft grippers for better grasping ability are highly desired. Inspired by the biological structure of octopuses, a class of temperature‐driven polylactic acid grippers is fabricated by 4D printing in this work, which consists of two types of bilayer structures, separately imitating the web and tentacles of an octopus. Compared with the traditional pure‐bending soft grippers, the integrated structure results in a 1.5 times wider reachable area and enhanced flexibility. The complex grasping behaviors are predicted with the 4D printing parameters (i.e., printing paths and printing speeds) using the reduced bilayer plate theory. Moreover, a method for determining the printing parameters of the gripper is provided to realize the desired grasping behavior depending on different objects. The feasibility of the design method is experimentally verified by gasping three distinctive objects, including an egg, a weight, and a Metatron's cube, which is in good agreement with the simulation results. Herein, a promising strategy is provided to achieve the easy‐fabricated, low‐cost, and versatile soft graspers using smart materials.

The molecular design of metal-free organic phosphors is essential for realizing persistent room-temperature phosphorescence (pRTP) despite its spin-forbidden nature. A series of halobenzonitrile–carbazoles has been prepared following a one-pot nucleophilic substitution protocol involving commercially available and laboratory-synthesized carbazoles. We demonstrate how halo- and cyano-substituents affect the molecular geometry in the crystal lattice, resulting in tilt and/or twist of the carbazole with respect to the phenyl moiety. Compounds obtained from the commercially available carbazole result in efficient pRTP of organic phosphors with a high quantum yield of up to 22% and a long excited state lifetime of up to 0.22 s. Compounds obtained from the laboratory-synthesized carbazole exhibit thermally activated delayed fluorescence with an excited state lifetime in the millisecond range. In-depth photophysical studies reveal that luminescence originates from the mixed locally excited state (3LE, nπ*)/charge transfer state.