IrIII-AuI luminescent bimetallic complexes have drawn growing interest for applications in photonics, catalysis, and biomedicine. Here, we report the synthesis of a new photoluminescent IrIII-AuI complex, the [(ppz)2Ir(mu-bbip)AuBr]PF6, incorporating 1,3-dibenzyl-1H-imidazo[4,5-f][1,10]phenanthrolin-3-ium bromide (bbip) as a bridging N-heterocyclic carbene (NHC) ligand. Among the various characterizations employed, single-crystal X-ray diffraction (SC-XRD) confirmed the structure of the complex, validating the proposed molecular formulation and coordination sphere. For comparative purposes and under similar conditions, the monometallic IrIII complex [Ir(ppz)2(bbip)](PF6)2 was synthesized and also validated by SC-XRD. Both complexes showed broad UV-vis excitation and orange-to-red emission in all tested solvents. Notably, the IrIII-AuI complex exhibited lower solvent polarity sensitivity than the mono-IrIII analog, with AuI coordination to bbip causing a slight emission blue shift. The incorporation of AuI significantly enhanced the photoluminescent properties, doubling both, the emission lifetime (tau) from 278 to 554 ns and the quantum yield (Phi) from 25 to 61% in degassed DCM. Notably, Phi remained high (30%) even in air-equilibrated DCM.

Zerovalent carbon compounds of the type L → C0 ← L, where L represents various ligands such as phosphines or carbenes, and C0 denotes zerovalent carbon with two orthogonal lone pairs, have been utilized in organic and coordination chemistry; however, in-depth photophysical and optical properties remain largely unknown. In the following work, we report detailed luminescent properties of one of the most prominent examples of zerovalent carbon compounds, hexaphenylcarbodiphosphorane (CDP). Combined spectroscopic/TD-DFT studies demonstrate that lone pairs of CDP participate in the observed visible light absorption and emission, which are associated with carbon lone pairs → π*(PPh3) carbon-to-ligand charge-transfer (CLCT) states. The CLCT state exhibits a considerably decoupled electron-hole pair, resulting in a small S1-T1 gap and thermally activated delayed fluorescence (TADF). Moreover, two nearly degenerate lone pairs on the C0 center provide multiple close-lying σ- and π-CLCT singlet and triplet states, which promote extremely fast rates of exergonic intersystem crossing (S1 → T1) up to 1.27 × 109 s-1, competitive with some 3d- and 4d-metal-based TADF luminophores. These results open fresh directions for the innovative design of novel luminescent materials for high-end photonic applications, utilizing lone pairs of zerovalent carbon centers as donors of electron density in the excited states.

IrIII-AuI luminescent bimetallic complexes have drawn growing interest for applications in photonics, catalysis, and biomedicine. Here, we report the synthesis of a new photoluminescent IrIII-AuI complex, the [(ppz)2Ir(μ-bbip)AuBr]PF6, incorporating 1,3-dibenzyl-1H-imidazo[4,5-f][1,10]phenanthrolin-3-ium bromide (bbip) as a bridging N-heterocyclic carbene (NHC) ligand. Among the various characterizations employed, single-crystal X-ray diffraction (SC-XRD) confirmed the structure of the complex, validating the proposed molecular formulation and coordination sphere. For comparative purposes and under similar conditions, the monometallic IrIII complex [Ir(ppz)2(bbip)](PF6)2 was synthesized and also validated by SC-XRD. Both complexes showed broad UV-vis excitation and orange-to-red emission in all tested solvents. Notably, the IrIII-AuI complex exhibited lower solvent polarity sensitivity than the mono-IrIII analog, with AuI coordination to bbip causing a slight emission blue shift. The incorporation of AuI significantly enhanced the photoluminescent properties, doubling both, the emission lifetime (τ) from 278 to 554 ns and the quantum yield (Φ) from 25 to 61% in degassed DCM. Notably, Φ remained high (30%) even in air-equilibrated DCM.

Two-coordinate, coinage metal carbene-metal-amide (cMa) emitters have garnered attention due to their near unity photoluminescence quantum yields, color tunability, and short radiative lifetimes. However, due to their intrinsically high energy HOMO and LUMO levels, there has been difficulty incorporating them into charge balanced organic light-emitting diodes (OLEDs). Here, four new cMa complexes were prepared where the HOMO was stabilized by using cyano or trifluoromethyl electron withdrawing groups on the donor moiety and the LUMO was stabilized using a carbene acceptor with a low reduction potential. These modifications resulted in cMa complexes with sky-blue emission, high quantum yields (ΦPL > 0.95), and short radiative lifetimes (τ = 225 ns). The resultant vacuum-deposited OLED devices based on Au Bim ( C F 3 ) 2 PAC ${\mathrm{Au}}_{{\mathrm{Bim}}{{{( {{\mathrm{C}}{{{\mathrm{F}}}_3}} )}}_2}}^{{\mathrm{PAC}}}$ with SiCzCz/SiTrzCz2 cohost system display blue electroluminescence at 470 nm and external quantum efficiency of 8%.

Abstract A series of gold(I) complexes featuring a novel ligand–gold–ynaminyl architecture was synthesized and characterized. The incorporation of a (carbazolyl)ethynide (C≡C-Cbz) ligand connects the photonic functionality of the carbazolyl with the N-heterocyclic carbene (NHC) through a long ethynide-Au bridge, showing shorter radiative lifetimes and higher ET values in solution in comparison to their carbene–metal–amido (CMA) congeners. The photophysical properties of the NHC complexes reveal a broad UV emission band when measured at room temperature and a hidden phosphorescence band with high quantum yield (up to 94%) at 77 K. This new photonic functional group based on polar ynamines is presented as a versatile platform for the design of high-energy gold-based luminophores with applications in photocatalysis.

We report the first uses of a copper carbene-metal-amido complex, [Cu(IPr)(Cbz)] (1), as an efficient photosensitizer for a broad range of triplet-triplet energy transfer (TTEnT) catalytic processes. Mechanistic studies confirm a triplet-triplet energy-transfer pathway. These findings establish 1 as the first copper-based photosensitizer competent in intermolecular [2+2] cycloaddition involving substrates with ET > 62 kcal/mol and hydrogen atom transfer via EnT, offering a cost-effective, sustainable alternative to noble-metal photocatalysts.

While the polymorphism of chalcopyrite semiconductors has been widely studied, the wurtzite analogues of defect-chalcopyrite II-III2-VI4 compositions, such as Zn(In,Ga)2(S,Se)4, remain underexplored. Here, we report the synthesis of polytypic Zn-(In,Ga)-Se multipods via cation exchange using ZnSe as a template. With zinc-blende cores and wurtzite arms elongated along the hexagonal c-axis, the multipods retain the structure and morphology of the ZnSe template. Optical characterization reveals composition-dependent absorption and photoluminescence, tunable from the visible to the near-infrared region, with spectral features distinct from those of previously reported defect-chalcopyrite structures. Temperature-dependent measurements demonstrate strong emission at cryogenic temperatures, which is quenched near room temperature due to thermally activated nonradiative processes. We illustrate the use of ZnSe as a platform for cation exchange toward wurtzite multinary chalcogenides, unlocking access to novel structures with colorful optical properties.

A series of Au(I) carbene-metal-amide (cMa) complexes using N-heterocyclic carbenes and N-benzo[d]benzo[4,5]imidazo[1,2-a]imidazolyl (bim) amide ligands have been synthesized as models to investigate coordination tautomerization in cMa compounds. Methyl substituents on the bim ligand were used to increase steric hindrance and break the degeneracy of tautomers. The presence of tautomers was identified using X-ray crystallography and 1H NMR spectroscopy, and the kinetics of tautomerization were measured. The dimethylbim (DMbim) ligand in cMa complexes thermodynamically favors a specific tautomer and suppresses the rate of tautomerization. The steric bulk of the NHC carbene and amide ligands and metal-carbene bond strength were found to alter the tautomerization rate. The photophysical properties of DMbim-based cMa are comparable to their bim-based analogs. The DMbim-based cMa complexes exhibit short emission lifetimes (tau = 200 ns) and fast radiative rates (k r = 4.9 x 106 s-1) with high photoluminescent quantum yields (Phi PL = 98%). Analysis of the temperature-dependent photophysical properties indicates fast lifetimes for the singlet state (tau = 14 ns) with small exchange energies (Delta E ST similar to 40 meV). The compounds provide general insight for rational molecular designs to suppress tautomerization.

The structural and photophysical properties of five chiral Zn complexes incorporating a carbazolate (Cz) donor that is electronically decoupled from a pyridyl acceptor by an ortho-connection to a bridging phenylene group are presented. The bidentate ligand in the unsubstituted bis-ligated parent complex was methylated at key positions to constrain the torsional freedom of the donor/acceptor moieties, resulting in three structurally modified bis-ligated derivatives, all exhibiting energy gaps between the singlet and triplet excited states (ΔEST) between 22 and 27 meV. Methylation improves the photoluminescence quantum yield (up to 30% in solution), while the low ΔEST of these complexes allows for dual-emission properties in all of the bis-ligated derivatives. Structural modification of the Cz/pyridyl ligand was also investigated by linking the unsubstituted bidentate ligand to generate a tetradentate, tetrapodal ligand. The solution-state structure of the tetradentate ligand is similar in its free and ligated forms, featuring a binding site reminiscent of enzymes and metal-sequestering ligands. The resulting tetradentate complex [Zn(N2R2)] shows enhanced through-bond conjugation, increasing the ΔEST to 89 meV, thereby eliminating the dual-emission characteristics of the bis-ligated complexes. Furthermore, this complex shows a 50-fold improvement in hydrolytic stability in organic solution relative to the parent complex. These compounds and their analyses are intended to enrich the understanding of compounds exhibiting through-space charge transfer and guide the search for earth-abundant metal complexes for applications in photosensitization and luminescence.

Hybrid metal halides are a remarkably dynamic family of materials that offer a flexible platform for exploring the novel crystal chemistry that emerges at the intersection of organic and inorganic solids. Herein, we report the discovery of a hybrid that contains two molecules effectively adopting isostructural geometry, (1-NA)PbI3 and (1-MQ)PbI3, and our attempts to create solid solutions of the two beyond the 1:1 ratio. Single-crystal X-ray diffraction, combined with solid-state NMR measurements, clearly show that despite having nearly identical steric geometry, the only mixed phase attained was the composition (1-MQ)(1-NA)Pb2I6, which exhibits a high degree of order between the two molecules. We propose that this ordering is primarily driven by local molecular dipoles, which ultimately creates a band structure in the blended phase that is highly characteristic of the end members, with little sign of rehybridization between the organic or inorganic components.

The performance of organic photovoltaic (OPV) devices has improved steadily since their introduction in the 1980's. The introduction of the bulk heterojunction and fullerene based acceptors in the early 2000’s led to a large bump in efficiency that led to photoconversion efficiencies > 10%. The next big step was int eh introduction of nonfullerene acceptors (NFAs), which replaced fullerenes with acceptor-donor-acceptor (ada) acceptors. The ada accepts shifted the absorption bands deep into the red end of the spectrum and gave OPVs with high short circuit currents. These ada materials are organic materials comprised of a range of donor and acceptor groups with an emphasis on thiophene based materials. We are investigating a different approach to ada (and dad) materials, incorporating porphyrin and dipyrrin donors as well as dipyrrin acceptors in the ada and dad structures. This has allowed us to prepare materials with absorption band edges deep into the nearinfrared, with HOMO/LUMO energies close to those of conventional ada materials. In my talk I will discuss our design strategies and most recent results with NFA comprised of porphyrin and dipyrrin building blocks as well as our most recent OPV results with these materials.

Polypyridines functionalized with pi-donating groups constitute a class of electron-rich ligands with significant relevance in coordination chemistry and catalysis. The incorporation of strongly basic guanidinyl substituents, however, often introduces multiple binding sites, with coordination typically favoring the guanidyl nitrogen atoms. Herein, we report the synthesis and characterization of a new electron-rich 1,10-phenanthroline ligand featuring bulky NHI groups that define a well-structured coordination cavity. Protonation studies and the preparation of a zinc(ii) complex reveal that Lewis acids preferentially coordinate at the phenanthroline nitrogen atoms rather than the NHI moiety. The electronic and photophysical properties of the new ligand and its complexes are explored through a combination of computational and experimental methods, demonstrating that its emission and absorption characteristics are highly sensitive to protonation, concentration, and metal coordination.

The photophysical properties of six new luminescent tetrahedral Zn(II) complexes are presented that survey two electronic donor moieties (phenolate and carbazolate) and three electronic acceptors (pyridine, pyrimidine, and pyrazine). A unique ligand based on an o-terphenyl motif forms an eight-membered chelate, which enhances through-space charge-transfer (CT) interactions by limiting through-bond conjugation between the donor and acceptor. A single isomeric product was obtained in yields up to 90%. Single-crystal X-ray diffraction structures of Zn complexes incorporating either donor show complementary interligand pi-pi interactions. All of the Zn complexes display long-lived luminescence in the solid state consistent with emission involving the triplet state. The phenolate-based complexes show evidence of CT emission in the solid state only with the strongest (pyrazinyl) acceptor. In contrast, all carbazolate-based complexes show evidence of thermally activated delayed fluorescence (TADF) in the solid and solution state, with photoluminescent quantum yields of up to 39%. These ligands represent a new family of Zn coordination compounds demonstrating TADF/phosphorescent properties that expand upon and elucidate design principles in the pursuit of photoactive earth-abundant metal complexes.

The expression of distinct microRNA (miRNA) species is associated with many major diseases, and thus, stable and reliable detection at low concentrations is crucial for early diagnosis and treatment. Field-effect transistor (FET)-based biosensors have shown significant progress in miRNA detection, but detection at ultralow concentrations remains challenging due to weak signal generation from small, low-charge miRNA molecules. Here, we report an In2O3 nanoribbon-based FET biosensor platform capable of detecting miRNAs at attomolar (aM) concentrations. Conventional surface functionalization approaches for metal-oxide-based FETs often involve complex, multistep protocols that are time-consuming and limit reproducibility. Here, we introduce a simplified one-step surface chemistry strategy with a 10-(maleimidyl)decylphosphonic acid (MalC10PA) linker molecule that addresses this limitation. We first demonstrated the detection of biotin-labeled miRNAs. Subsequently, we have further demonstrated a label-free miRNA sensing technique by employing an uncharged peptide nucleic acid (PNA) probe/target RNA/secondary DNA-biotin sandwich structure, followed by the introduction of streptavidin and biotin-urease. The urease-induced pH changes amplify the detection of charge changes in the In2O3 channel region, significantly improving the biosensor's sensitivity. The electrolyte-gated In2O3-FET biosensors achieved an ultralow detection limit of 0.72 aM in buffer and high selectivity over miRNAs with two and three base-pair mismatches. Furthermore, the detection of miRNAs from patient plasma exhibited consistent signal compared to the detection in buffer. The detection of specific miRNA species is of recognized importance in early cancer detection and evaluation, and our described method demonstrates great potential for highly multiplexed detection technology with ultrahigh sensitivity.

Energy transfer photocatalysis has emerged as a powerful platform for a wide variety of transformations, yet advances in this area are often limited by the visible-light absorption of catalysts and the very high cost of state-of-the-art iridium-based sensitizers. We report the synthesis, characterization, and photocatalytic use of a novel digold(I) complex, {[Au(IPr)]2(DHIC)} (PhotAu3), designed to overcome these limitations by absorbing visible light in the blue region and proving catalytically effective under 450 nm LED irradiation. The complex was successfully applied to a range of EnT-mediated photocatalytic reactions, including intramolecular [2 + 2] cycloadditions and E/Z isomerizations, achieving high conversions at low catalyst loadings in short reaction times.