Iodide Ligands Research Articles

Enhanced carrier transfer performance on blade-coating PbS quantum dot solar cells by coordinated operation of iodine ligands

The significant breakthrough in the photovoltaic conversion efficiency of lead sulfide (PbS) quantum dot solar cells has primarily been achieved on small substrates using the spin-coating method. However, the blade-coating technique offers a scalable alternative for large-scale fabrication of absorption film, addressing the limitations of spin-coating for commercial applications. Given the inherent challenges of the blade-coating method, which often produces low-quality and defective films. Thus, an iodide ligand passivation strategy to realize the formation of high-quality films with reduced trap states was proposed. Typically, the iodide ligand is incorporated into the precursor solution with the aim of fine-tuning the nanoparticle’s functionality, facilitating the formation of systematically aligned and densely coupled film configurations during the blade coating procedure. The functional mechanisms of the aligned and compact-coupled configurations, as well as the effect of iodide introduction on defect mitigation, have been systematically investigated. The results reveal that iodide ligand introduction modulates the interparticle electrostatic potential and inter-dot space, facilitating the formation of a uniform structure with enhanced energy level alignment and reduced trap states. The highly aligned and compact structure improves interfacial integration with the ZnO electron transport layer, enabling efficient photon-electron extraction and transfer. As a result, PbS quantum dot solar cells fabricated using the blade coating technique have achieved an optimized efficiency of 4.68 %, offering significant potential for the development and production of directly-synthesized ink for quantum dot solar cells.

The Rectangular Niobium Oxyiodide Cluster Nb4OI10 – A Narrow Band‐Gap Semiconductor

AbstractA metal‐rich niobium oxyiodide was prepared by soft reduction of NbI4. The structure of the new compound Nb4OI10 was determined by single‐crystal X‐ray diffraction and contains a rectangular Nb4(μ4‐O) cluster that is interconnected into layers by iodide ligands. The local structure of the Nb4OI10 cluster bears a close relationship to a defect Nb6I11 structure. The two‐dimensional van der Waals material Nb4OI8I4/2] is a small band‐gap semiconductor (<1 eV), as analysed by electrical conductivity measurements, photoresponse, experimental band gap determination, and band structure calculation.

Potassium, ytterbium(II), and samarium(III) alkoxide complexes containing the <i>tris</i>((2-dimethylaminomethyl)phenyl)methoxide ligand: synthesis and structures

The reaction oftris((2-dimethylaminomethyl)phenyl)methanol ((2-Me2NCH2C6H4)3COH) with potassium hydride in THF at –35°C affords dimeric alkoxide {[(2-Me2NCH2C6H4)3CO]K(THF)}2(I) in a yield of 90%. The reaction of compound I with YbI2(THF)2(1 : 1, 25°C) gives the Yb(II) alkoxyiodide complex {[(2-Me2NCH2C6H4)3CO]Yb(μ-I)(THF)2}2(II) in a yield of 57%. Complex II in the crystalline state is dimeric due to two bridging iodide ligands. Unlike the Yb(II) compound, the exchange reaction of complex I with SmI2(THF)2 (1 : 1, 25°C) in THF followed by the addition of dimethoxyethane (DME) involves the oxidation of the metal to form the trivalent samarium complex [(2-Me2NCH2C6H4)3CO]2SmI (III), which is isolated in a yield of 60%. The molecular structures of the complexes are determined by X-ray diffraction (XRD) (CIF files CCDC nos. 2259700 (I), 2259701 (II), and 2259702 (III)).

Silver Organometallics that are Highly Potent Thioredoxin and Glutathione Reductase Inhibitors: Exploring the Correlations of Solution Chemistry with the Strong Antibacterial Effects.

The antibacterial activity of silver species is well-established; however, their mechanism of action has not been adequately explored. Furthermore, issues of low-molecular silver compounds with cytotoxicity, stability, and solubility hamper their progress to drug leads. We have investigated silver N-heterocyclic carbene (NHC) halido complexes [(NHC)AgX, X = Cl, Br, and I] as a promising new type of antibacterial silver organometallics. Spectroscopic studies and conductometry established a higher stability for the complexes with iodide ligands, and nephelometry indicated that the complexes could be administered in solutions with physiological chloride levels. The complexes showed a broad spectrum of strong activity against pathogenic Gram-negative bacteria. However, there was no significant activity against Gram-positive strains. Further studies clarified that tryptone and yeast extract, as components of the culture media, were responsible for this lack of activity. The reduction of biofilm formation and a strong inhibition of both glutathione and thioredoxin reductases with IC50 values in the nanomolar range were confirmed for selected compounds. In addition to their improved physicochemical properties, the compounds with iodide ligands did not display cytotoxic effects, unlike the other silver complexes. In summary, silver NHC complexes with iodide secondary ligands represent a useful scaffold for nontoxic silver organometallics with improved physicochemical properties and a distinct mechanism of action that is based on inhibition of thioredoxin and glutathione reductases.

Modified surface ligand management of CsPbI3 perovskite quantum dots enables efficient and stable electroluminescent solar cells

Solution-processed CsPbI3 perovskite quantum dots (PQDs) have attracted enormous attention in both photovoltaic and electroluminescent applications in recent years. However, the surface defects of CsPbI3 PQDs in the ligand exchange procedure still suffer the challenge of imperfect passivation, leading to poor device performance and ambient stability. In this work, we propose a modified surface ligand management to deposit CsPbI3 PQD films using a layer-by-layer (LBL) solid-state exchange strategy, and its applications in photovoltaic and electroluminescent devices are studied. The conjugated phenethylammonium iodide (PEAI) ligand, acting as a short-chain ligand with a phenyl group (PEA+ ion) for encapsulating the CsPbI3 PQDs during the LBL procedure, which can both realize enhanced inter-dot coupling and defects passivation compared with conventional post-treatments. We further demonstrate the balanced transport and injection of electrons and holes within the PEAI-LBL based CsPbI3 PQD films. With this approach, the CsPbI3 PQD solar cells based on PEAI-LBL yielded a champion power conversion efficiency (PCE) of up to 14.18% with a high open voltage of 1.23 V, along with obviously electroluminescent red emission properties in one device. Meanwhile, the unencapsulated devices exhibited excellent stability under a high-humidity environment. This strategy should accelerate advancement in utilizing PQDs for bifunctional optoelectronic applications.

PbS Quantum Dots Ink with Months-Long Shelf-Lifetime Enabling Scalable and Efficient Short-Wavelength Infrared Photodetectors.

The phase-transfer ligand exchange of PbS quantum dots (QDs) has substantially simplified device fabrication giving hope for future industrial exploitation. However, this technique when applied to QDs of large size (>4nm) gives rise to inks with poor colloidal stability, thus hindering the development of QDs photodetectors in short-wavelength infrared range. Here, it is demonstrated that methylammonium lead iodide ligands can provide sufficient passivation of PbS QDs of size up to 6.7nm, enabling inks with a minimum of ten-week shelf-life time, as proven by optical absorption and solution-small angle X-ray scattering. Furthermore, the maximum linear electron mobility of 4.7×10-2cm2V-1s-1 is measured in field-effect transistors fabricated with fresh inks, while transistors fabricated with the same solution after ten-week storage retain 74% of the average starting electron mobility, demonstrating the outstanding quality both of the fresh and aged inks. Finally, photodetectors fabricated via blade-coating exhibit 76% external quantum efficiency at 1300nm and 1.8×1012Jones specific detectivity, values comparable with devices fabricated using ink with lower stability and wasteful methods such as spin-coating.

Substitution of apical iodide ligands in octahedral molybdenum cluster complexes by N-donor molecules: Synthesis and investigation of [{Mo6I8}(L)I5]– and cis-[{Mo6I8}(L)2I4] (L = CH3CN or 1,2,4-triazole)

In this work, reactivity of the [{Mo6I8}I6]2– cluster anion toward some N-donor ligands was investigated. Heating of the solution of Cs2[{Mo6I8}I6] salt in acetonitrile leads to the partial substitution of apical iodide ligands by CH3CN molecules forming crystalline solid Cs0.1[{Mo6I8}(CH3CN)I5]0.1·cis-[{Mo6I8}(CH3CN)2I4]0.9·0.9CH3CN (1). The solid includes anionic [{Mo6I8}(CH3CN)I5]– and neutral cis-[{Mo6I8}(CH3CN)2I4] cluster units at a ratio of 1:9. In the crystal structure of 1, these clusters occupy common crystallographic sites, which allows us to consider this compound as a solid solution. When 1,2,4-triazole (tz) was added to the reaction mixture, a solid solution of mono- and disubstituted products was also formed and crystallized in a ratio of approximately 1:3, yielding the compound Cs0.27[{Mo6I8}(tz)I5]0.27·cis-[{Mo6I8}(tz)2I4]0.73 (2). It was assumed that compound 2 was formed as a product of direct substitution of the apical iodide ligands by tz molecules. Structural features and luminescence properties of the new compounds 1 and 2 were studied.

Bent-Linear Isomerism and a Caveat on Bond Angle Distortion Anomalies in CpMo(NO)(η3-Methallyl)NCO

The displacement of the iodide ligand in (+)-(Cp)Mo(NO)(η3-methallyl)I, (+)-1, by treatment with silver(I) isocyanate yields (+)-(Cp)Mo(NO)(η3-methallyl)(NCO), (+)-2, with retention of configuration at the metal and was found to have the SMo configuration by X-ray crystallography. The X-ray data also showed the presence of two structure types in the unit cell of (+)-2, one bent and one linear with ∠MoNC bond angles of 154.4(4)° and 173.4(4)° respectively. In contrast, crystals of rac-2 show only one structure in the solid with an intermediate angle of 165.7(4). If (+)-2 is prepared via conversion of (+)-1 first to the carbonyl, by abstraction of iodide and treatment with CO, and subsequently sodium azide, yielded crystals of (+)-2 which showed varying angles ∠MoNC that appeared to be distortion isomers. Closer inspection of these products revealed an admixture of the intermediate azide compound, (+)-(Cp)Mo(NO)(η3-methallyl)N3, (+)-3, in the sample that was predominantly (+)-2. Mixtures of (+)-3 and (+)-2 or (-)-3 and (-)-2-co-crystallize and the results of X-ray structures of such mixtures appear to show 2 with varying bond angles ∠MoNC depending on the percentage of 3 in them. For example crystals with 85% of (-)-2 show ∠MoNC bond angles of 148.9(5)° and 171.9(5)°. This compares with the ∠MoNN in pure azide (+)-3 of 123.7(6)°

Metal-Involving Halogen Bonding Confirmed Using DFT Calculations with Periodic Boundary Conditions

The cocrystallization of trans-[PtI2(NCN(CH2)5)2] and iodoform (CHI3) yields crystalline adduct trans-[PtI2(NCN(CH2)5)2]∙2CHI3, the structure of which was studied via single-crystal X-ray diffractometry (XRD). In the XRD structure of trans-[PtI2(NCN(CH2)5)2]∙2CHI3, apart from rather predictable C–H∙∙∙I hydrogen bonds (HBs) and C−I∙∙∙I halogen bonds (XBs) with the iodide ligands, we identified C–I∙∙∙Pt metal-involving XBs, where the platinum center functions as an XB acceptor (that includes a metal dz2-orbital) toward the σ-holes of I atoms of CHI3. DFT calculations (PBE-D3/jorge-TZP-DKH with plane waves in the GAPW method) were carried out in the CP2K program for isolated molecules, complex–iodoform clusters, and crystal models with periodic boundary conditions, where the noncovalent nature and the existence of the interactions were confirmed using charge analysis, Wiberg bond indexes, and QTAIM topology analysis of electron density, whereas the philicities of the noncovalent partners were proved using charge analysis, electron localization function, electron density deformation, and one-electron potential projections, as well as electron density/electrostatic potential profiles for cluster models and electrostatic potential surfaces (ρ = 0.001 a.u.) for isolated molecules.

Stabilization of PbS colloidal-quantum-dot gas sensors using atomic-ligand engineering

Colloidal quantum dots (CQDs) are promising materials candidates for next-generation semiconductor gas sensors, due to their high surface activity and solution-processability. Despite the improved sensitivity demonstrated by PbS CQDs, their long-term stability remains a challenge for practical applications. In this paper, we propose a stabilization strategy for PbS CQD gas sensors by using atomic-ligand engineering. The oleic acid ligands surrounding PbS CQDs are replaced by halide ligands (Cl–, Br– and I–, respectively) via a phase-transfer ligand exchange method. The sensitivity and long-term stability of the PbS CQD gas sensor towards nitrogen dioxide (NO2) at room temperature are impressively improved. The excellent humidity stability of the iodine ligand exchanged PbS CQD gas sensor is also demonstrated. The mechanism is investigated by real-time electrical measurement, combined with operando diffuse reflection Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy analysis. The results indicate that the large atomic radius and high binding energy of iodide ligands enhance surface passivation and provide favorable conditions for NO2 adsorption and charge transfer. This study highlights the importance of surface ligand engineering in the development of practical CQD gas sensors.

2d, or Not 2d: An Almost Perfect Mock of Symmetry

The paper is related to an interesting case of revision of X-ray crystal structure with a lack of experimental data. Complexes V4OSe8I6·X (X = I2 or 3,5-dimethylpyrazole) with O-centered complex molecules [V4O(μ-Se2)4I4(μ-I)2] were synthesized in our group. In the further search for new relative compounds in the V-Se-I-O system, we obtained several crystals with different structures, including “V4OSe6I3”, with incredibly complicated connectivity of {V4O(Se2)4I6} units bridged via both diselenide and iodide ligands. Due to the absence of phase-pure products and the possible instability of some of the phases under ambient conditions, we were mainly guided by the single-crystal X-ray diffraction data. However, seeing a very complex coordination mode in the “V4OSe6I3” structure, we have carefully analyzed the structure from the positions of symmetry and chemical synthesis in this system. The “new structure” was recognized as the complex superposition of the structure of another compound with composition “V4OSe6I10” just found in the same experiment. We outlined the course of observations, reasoning and solutions to the symmetry false estimation problem, which we believe to be of interest to readers dealing with X-ray diffraction analysis.

Synthesis, crystal structure and Hirshfeld surface analysis of di-μ2-iodido-bis-[(2,2'-bi-quinoline-κ2 N,N')copper(I)

The mol-ecular and crystal structures of the title compound, [Cu2I2(C18H12N2)2], were examined by single-crystal X-ray diffraction and Hirshfeld surface analysis. The Cu atom is coordinated in a distorted tetra-hedral geometry by two N atoms from the 2,2'-bi-quinoline ligands and the two μ2-bridging iodide ligands. The mol-ecules are in contact via π-π-stacking inter-actions. Hirshfeld surface analysis showed that the most important contributions to the inter-molecular inter-actions are H⋯H (39.7%), H⋯I/I⋯H (17.8%), C⋯H/H⋯C (17.5%), C⋯C (16.5%), N⋯C/C⋯N (3.9%) and N⋯H/H⋯N (3.5%).

On the competition between six-membered and five-membered NHC towards alane centered ring expansion.

The combination of 6-SIDipp·AlH3 (1) and 5-IDipp resulted in the ring expansion of 6-NHC, while the five-membered NHC remained unchanged, which was subsequently explained by DFT studies. Besides, the substitution chemistry of 1 was also studied with TMSOTf and I2, which gave rise to the substitution of a hydride by triflate or iodide ligands.

Silver N-heterocyclic carbene complexes are potent uncompetitive inhibitors of the papain-like protease with antiviral activity against SARS-CoV-2.

The ongoing SARS-CoV-2 pandemic has caused a high demand for novel innovative antiviral drug candidates. Despite promising results, metal complexes have been relatively unexplored as antiviral agents in general and in particular against SARS-CoV-2. Here we report on silver NHC complexes with chloride or iodide counter ligands that are potent inhibitors of the SARS-CoV-2 papain-like protease (PLpro) but inactive against 3C-like protease (3CLpro) as another SARS-CoV-2 protease. Mechanistic studies on a selected complex confirmed zinc removal from a zinc binding domain of PLpro as relevant factor of their activity. In addition, enzyme kinetic experiments revealed that the complex is an uncompetitive inhibitor and with this rare type of inhibition it offers great pharmacological advantages in terms selectivity. The silver NHC complexes with iodide ligands showed very low or absent host cell toxicity and triggered strong effects on viral replication in cells infected with SARS-CoV-2, making them promising future antiviral drug candidates.

Luminescent fac-[ReX(CO)3(phenyl-pyta)] (X = Cl, Br, I) complexes: influence of the halide ligand on the electronic properties in solution and in the solid state.

Tricarbonylrhenium(I) complexes that incorporate a chloride ligand are promising photoluminescent materials, but those incorporating a bromide or iodide ligand have received very little attention regarding their solid-state properties. In this work, three rhenium(I) complexes differing only by the nature of their halide ligand (X = Cl, Br, and I) were compared. They are based on a fac-[ReX(CO)3(N^N)] framework where the N^N bidentate ligand is a 3-(2-pyridyl)-1,2,4-triazole unit functionalized by an appended phenyl group. DFT calculations showed that the character of the lowest energy transitions progressively changes from Re → N^N ligand (MLCT) to X → N^N ligand (XLCT) when increasing the size of the halogen atom. Regarding the electrochemical behavior, the chloride and bromide complexes 1-Cl and 1-Br were similar, while the iodide complex 1-I exhibited a strikingly different electrochemical signature in oxidation. From a spectroscopic viewpoint, all three complexes emitted weak red-orange phosphorescence in dichloromethane solution. However, in the solid state, marked differences appeared. Not only was 1-Cl a good emitter of yellow light, but it had strong solid-state luminescence enhancement (SLE) properties. In comparison, 1-Br and 1-I were less emissiveand they showed better mechanoresponsive luminescence (MRL) properties, probably related to a loose molecular arrangement in the crystal packing and to the opening of vibrational non-radiative deactivation pathways. This study highlights for the first time how the nature of the halide ligand in this type of complex allows fine tuning of the solid-state optical properties, for potential applications either in bio-imaging or in the field of MRL-active materials.

Deep‐Red Perovskite Light‐Emitting Diodes with External Quantum Efficiency Exceeding 21% Enabled by Ligand‐Modulated Dimensionality Control

AbstractQuasi‐2D perovskites show great promise for light‐emitting diodes owing to suppressed non‐radiative losses enabled by the energy funneling/cascading nanostructures. However, for red emission quasi‐2D perovskites, these ideal energy landscapes for efficient perovskite light‐emitting diodes (PeLEDs) can rarely be achieved due to detrimental aggregation of the low‐dimensional ligands in perovskite precursors, leading to poor device efficiency and stability. Here, a ligand‐modulated dimensionality control strategy is explored to achieve uniform phase distribution and reduce defect density for efficient light emission. In contrast to the model phenethylammonium iodide 2D ligand, the formation of small‐n phases can be inhibited by a structurally similar phenoxyethylammonium iodide ligand owing to the weakened aromatic stacking between ligands. Besides, the oxygen atoms can interact with the uncoordinated Pb2+ ions and promote the NI coordination in the perovskites, which greatly reduces the non‐radiative recombination defects in the ionic lattice. With this simple and effective approach, deep‐red quasi‐2D PeLEDs with record‐high external quantum efficiency of 21.6% and decent operational stability are achieved without the need for additional additives. These results highlight the potential of ligand‐modulated dimensionality control to achieve highly efficient and stable PeLEDs with a facile fabrication process.

Reducing the interfacial voltage loss in tin halides perovskite solar cells

Tremendous attention has been given to tin halide perovskite solar cells (TPSCs) due to the lower toxicity and similar electronic configuration compared with the lead perovskites. Nevertheless, on account of the intrinsic low bandgap, high defect density and surface/interface non-radiative recombination, the open-circuit voltage loss (Vloss) of TPSCs is comparatively large in all semiconductor solar cells. Herein, a hydrophobic bulky molecule of 3-(trifluoromethyl) phenethylamine hydroiodide (CF3PEAI) was utilized to passivate the lead-free perovskite surface by post-deposition treatment. The Vloss of the corresponding PSC devices was significantly reduced to afford a high open-circuit voltage (Voc) up to 0.73 V with a power conversion efficiency (PCE) of 10.35% in conjunction with the broadly utilized (6,6)-Phenyl C61 butyric acid methyl ester (PC61BM). Additionally, the CF3PEAI interlayer expressively suppressed the interfacial non-radiative recombination accompanying with extending photoexcited carrier lifetime. The formation of oriented 2D Sn-based perovskite could also facilitate the vertical charge-carrier transportation and improve the efficiency of Sn-based PSCs. The density of defect states and the amount of mid-gap states required to be filled were both dramatically reduced. Meanwhile, the surface reconstruction can effectively relax the tensile surface strain with the phenethyl ammonium iodide ligands. Therefore, this surface passivation strategy contributes to the development of high-quality lead-free perovskite film with low internal defects and residual stress.

Halogen Bonding and CO-Ligand Blue-Shift in Hybrid Organic—Organometallic Cocrystals [CpFe(CO)2X] (C2I4) (X = Cl, Br)

This work is focused on the complex interplay of geometry of I⋯X halogen bonds (HaB) and intermolecular interaction energy in two isomorphic cocrystals [CpFe(CO)2X] (C2I4) (X = Cl (1), Br (2)). Their IR-spectroscopic measurements in solid state and solution demonstrate the blue-shift of CO vibration bands, resulting from I⋯X HaB. The reluctance of their iodide congener [CpFe(CO)2I] to form the expected cocrystal [CpFe(CO)2I] (C2I4) is discussed in terms of different molecular electrostatic potential (MEP) of the surface of iodide ligands, as compared with chloride and bromide, which dictate a different angular geometry of HaB around the metal-I and metal-Br/Cl HaB acceptors. This study also suggests C2I4 as a reliable HaB donor coformer for metal-halide HaB acceptors in the crystal engineering of hybrid metal–organic systems.

Enantiopure Cyclometalated Rh(III) and Ir(III) Complexes Displaying Rigid Configuration at Metal Center: Design, Structures, Chiroptical Properties and Role of the Iodide Ligand

Enantiopure N-heterocyclic carbene half-sandwich metal complexes of the general formula [Cp*M(C^C:)I] (M = Rh, Ir; C^C: = NI-NHC; NI-H = Naphthalimide; NHC = N-heterocyclic carbene) are reported. The rhodium compound was obtained as a single isomer displaying six membered metallacycle and was resolved on chiral column chromatography to the corresponding enantiomers (S)-[Cp*Rh(C^C:)I] (S)-2 and (R)-[Cp*Rh(C^C:)I] (R)-2. The iridium congener, however, furnishes a pair of regioisomers, which were resolved into (S)-[Cp*Ir(C^C:)I] (S)-3 and (R)-[Cp*Ir(C^C:)I] (R)-3 and (S)-[Cp*Ir(C^C:)I] (S)-4 and (R)-[Cp*Ir(C^C:)I] (R)-4. These regioisomers differ from each other, only by the size of the metallacycle; five-membered for 3 and six-membered for 4. The molecular structures of (S)-2 and (S)-4 are reported. Moreover, the chiroptical properties of these compounds are presented and discussed. These compounds display exceptional stable configurations at the metal center in solution with enantiomerization barrier ΔG≠ up to 124 kJ/mol. This is because the nature of the naphthalimide-NHC clamp ligand and the iodide ligand contribute to their configuration’s robustness. In contrast to related complexes reported in the literature, which are often labile in solution.

C(sp3 )-H Arylation Promoted by a Heterogeneous Palladium-N-Heterocyclic Carbene Complex in Batch and Continuous Flow.

A heterogeneous reusable palladium(II)‐bis(N‐heterocyclic carbene) catalyst was prepared and shown to catalyze the intramolecular C(sp3)−H activation/cyclization of N‐alkyl‐2‐bromoanilines furnishing indolines. This new catalytic system was based on a bis‐imidazolium ligand immobilized on a spaced cross‐linked polystyrene support. The iodide ligands on the catalyst played a central role in the efficiency of the process occurring through a “release and catch” mechanism. The heterogeneous nature of the catalyst was further exploited in the design of a continuous‐flow protocol that allowed a more efficient recovery and reuse of the catalyst, as well as a very fast and safe procedure.