Sandwich Complexes Research Articles

Nature of Cation‐π Interaction in Mono‐ and Inverted Sandwich Ga(I) Complexes. Insights Into the Ga(I)‐π Features and NMR Patterns from GaCp, GaCp*, [Ga2Cp]+, and [Ga2Cp*]+

AbstractCation‐π interactions involve different metallic cations, where the bonding characteristics depend on the involved species. Here, we unravel the interaction nature features for Ga(I)‐π interactions, where different contributing terms ensure an efficient coordination of one and two Ga(I)‐atoms towards a common aromatic ring. Our results show a more balanced contribution of about ~70 % from electrostatic character and of ~30 % from orbital interaction for the prototypical GaCp, GaCp*, [Ga2Cp]+ and [Ga2Cp*]+ species. Such description strongly contrasts with the highly electrostatic character in alkali and alkaline‐earth metals counterparts. The variation from mono to inverted sandwich complexes leads to a decrease in the interaction energy from −180.9 to −148.1 kcal/mol for Cp based species, and from −184.4 to −155.5 kcal/mol in Cp* counterparts, owing to a decrease in both electrostatic and orbital stabilizing contributions. Thus, the aromatic rings exhibit coordination versatility towards one or two Ga(I) cations, retaining a sizable stabilization of the Ga(I)‐π interaction. Thus, cation‐π interactions are able to exhibit different types according to the involved metal cation, which relies on a more electrostatic/orbital balanced interaction, which serves to evaluate further mono and inverted sandwich complexes sharing a common aromatic ring.

Dual-signal biosensor based on G-quadruplex/hemin DNAzyme and zinc-doped molybdenum disulfide quantum dots for ultrasensitive detection of tumor biomarker

Herein, a dual-mode fluorometric and colorimetric biosensor for Pax-5a gene was developed based on zinc-doped molybdenum disulfide quantum dots (Zn-MoS2 QDs) by coupling exonuclease-assisted recycling amplification and peroxidase-mimic DNAzyme. In the presence of Pax-5a gene, the exonuclease III can cleave the duplexes formed by Pax-5a gene and the hairpin DNA (HP), releasing the output DNA (oDNA). G-rich DNA and magnetic beads (MBs) labeled with capture DNA (cDNA) can hybridize with oDNA to form the MBs-cDNA/oDNA/G-rich DNA sandwich complex. The remaining G-rich DNA in the supernatant through magnetic separation could bind hemin to produce G-quadruplex/hemin peroxidase-mimicking DNAzyme, which catalyzed the oxidization of 3,3'-diaminobenzidine (DAB) by H2O2. The generated brown oxidation product (oxDAB) had a distinct absorption peak at 464 nm and could quench the fluorescence of Zn-MoS2 QDs at 406 nm. The high peroxidase activity of DNAzyme, recycling amplification strategy and magnetic separation technique led to excellent sensitivity and specificity of this detection platform. The detection limits of Pax-5a gene by fluorometric and colorimetric methods were 0.52 pM and 1.12 pM, respectively. Furthermore, this sensing system was successfully applied to Pax-5a gene determination in human serum samples, which had promising potential in biochemical analysis and clinical diagnosis.

A clenbuterol detection method based on magnetic separation up-conversion fluorescent probe

In this study, a fluorescence detection method combining aptamer-modified up-conversion nanoparticles (UCNPs) and magnetic nanoparticles (MNPs) was developed for detection of Clenbuterol (CLB). The aptamer-modified magnetic NPs captured CLB, which reacted with the aptamer-modified UCNPs and generated a sandwich complex. The aptamer-modified UCNPs acted as a fluorescence source. The MNP-CLB-UCNP complex was retrieved from the solution using an magnetic field, and the fluorescence intensity was detected by fluorescence spectrophotometry with excitation and emission spectra at 980 nm and in the 400–800 nm region, respectively. The results showed that the fluorescence intensity gradually increased with increasing concentrations of CLB with a good specify. The method was highly sensitive for the quantification of CLB, with a limit of detection of 0.304 ng mL−1. The recovery rate of CLB from pork samples ranged from 84 % to 94.87 %. This fluorescence method enables the sensitive, precise, and accurate quantification of CLB residues in pork samples.

Electrocatalytic CO2 reduction to HCO2H by protic NHC-Ir complexes

In electrochemical CO2-conversion strategies, various transition metal-based molecular electrocatalysts are employed to reduce CO2 into products like CO and HCO2H, with H2 as a competitive side product. However, achieving selectivity towards HCO2H remains challenging, and suitable catalysts for the same are limited. Herein we report a normal and an abnormal protic-NHC-based Cp*Ir(III)-half sandwich complexes for catalytic CO2 electroreduction in an aqueous acetonitrile solvent. Both the catalysts predominantly produced HCO2H as the CO2-reduced product at an applied potential of –2.66 V vs Fc+/Fc with 5 % H2O as the proton source; however, the normal protic-NHC-bound complex achieved a Faradic efficiency (FE) of 86±4 %, while the complex with the abnormal protic-NHC ligand furnished FE up to 72±4 %. The protic proton of the protic NHC ligand in these complexes was proposed to participate in a proton relay process, facilitating generation of the crucial Ir–H intermediate, which reacts with CO2 to produce HCO2H through stabilization of the Ir–OCHO intermediate.

Highly Sensitive Electrochemiluminescence Biosensing Method for SARS-CoV-2 N Protein Incorporating the Micelle Probes of Quantum Dots and Dibenzoyl Peroxide Using the Screen-Printed Carbon Electrode Modified with a Carboxyl-Functionalized Graphene.

Obtaining stable electrochemiluminescence (ECL) emissions from a hydrophobic luminophore in aqueous solutions and designing a method without the use of an exogenous coreactant are promising for ECL biosensing. Here, a highly sensitive signal-on ECL immunoassay for the SARS-CoV-2 N protein was developed using micelles as an ECL tag. The micelles were prepared by coencapsulating the luminophore hydrophobic CdSe/ZnS quantum dots and coreactant dibenzoyl peroxide within the hydrophobic core of micelles. The ECL probe was obtained by covalently bonding a SARS-CoV-2 N protein-binding aptamer onto the micelle surface. The construction of the immunosensor was initiated by the immobilization of the anti-SARS-CoV-2 N protein antibody onto the screen-printed carbon electrode (SPCE) with a -COOH-functionalized surface. The surface functionalization of SPCEs was achieved through paste-exfoliated graphene, which was modified with a -COOH group through supramolecular-covalent scaffolds on SPCE. Upon achieving sandwich complexes on the immunosensor, an efficient ECL signal response at -1.4 V versus Ag/AgCl was obtained in phosphate buffer solution. The ECL assay was used for the sensitive determination of SARS-CoV-2 N protein with the linear range from 0.01 to 50 ng mL-1, and the detection limit was 3.0 pg mL-1. The immunosensor showed good reproducibility and stability, and the ECL immunoassay was used to determine the SARS-CoV-2 N protein in serum samples. The proposed approach to obtain micelles is versatile for the preparation of stable ECL luminophores by using hydrophobic materials, and the strategy provides an alternative for ECL bioassays based on the coreactant route.

Exploring the Magnetism of C5/C2B3 Heteroleptic Organolanthanide Sandwiches

Comprehensive SummaryTwo families of cyclopentadienyl (Cp)/carboranyl heteroleptic sandwiched organolanthanide complexes, namely [Ln{η5:σ‐Me2C(C5H4)(C2B10H10)}2][Li(DME)3] (1Ln, Ln = Tb, Dy, Ho, Er) and [2‐THF‐2'‐(μ2‐Cl)Li(THF)3‐2,2'‐Ln(nido‐1,7‐C2B9H11)Cp*] (2Dy), were synthesized. Family of 1Ln has been proposed based on the mixing‐ligands idea by linking Cp and nido‐dicarborllide. However, the carborane cage of [Me2C(C5H4)(C2B10H10)]2− deprotons and forms a mono‐C− anion rather than deboron to form dicarborllide dianion. Hence, the family of 1Ln features a dysprosocenium skeleton with extra two coordination of C− anions of carborllides. Such coordination geometry is more like a tetrahedron if abstracting the centroids of two coordinated Cp rings. In this cubic‐type geometry, no significant magnetic axiality is presented; only 1Dy and 1Tb show field‐induced slow magnetic relaxation behavior below 10 K. Inspired by 1Ln, the free pentamethylcyclopentadienyl (Cp*−) and nido‐dicarborllide ligands are used to sandwich central Dy3+ ion, achieving heteroleptic complex 2Dy. The bending angle by linking the centroid of Cp*−, Dy3+ and C2B32− in 2Dy is increased to 132.8(1)°. As such, the effective energy barrier for magnetic reversal (Ueff) and magnetic blocking temperature TB (ZFC) are both increased (Ueff = 616(10) K; TB = 6 K). The effort of further enhancing Ueff and TB in such heteroleptic organolanthanide sandwiches should rely on keeping increasing the ligand axiality.

Three birds with one stone: A nano zeolitic imidazolate framework-luciferase-antimicrobial peptide biocomposite-based biosensing platform for improving enzyme stability, detection sensitivity, and sterilization effect

Adenosine triphosphate-driven bioluminescence (ATP-BL) biosensors were widely employed for on-site screening of bacteria. However, unstable luciferase with strict storage conditions limited its field detection. Moreover, the traditional ATP-BL biosensors lacked the sterilization effect. In this study, a robust and multifunctional zeolitic imidazolate framework-90 decorated with luciferase and polyethylene glycol–antimicrobial peptides (ZIF-90@Luc-AMP) was prepared. It could not only enhance the activity and stability of luciferase at ambient temperatures (≥1 month) but also sensitively detect target bacteria via the bioluminescence (BL) method and kill them (three birds with one stone). During the detection process, the target pathogen Escherichia coli O157:H7 (E. coli O157:H7) was specifically captured on a phage-modified stir bar and formed a sandwich complex with ZIF-90@Luc-AMP. With the synergistic bacteriolysis of ZIF-90@Luc-AMP and the phage, the captured E. coli O157:H7 was decomposed and emitted adenosine triphosphate (ATP), achieving the sterilization effect. Meanwhile, the introduced luciferase catalyzed ATP to produce a BL signal, which was proportional to the concentration of E. coli O157:H7. Combining ZIF-90@Luc-AMP and a phage-labeled stir bar for target recognition and enrichment, the entire analytical process could be easily manipulated within 30 min with a low limit of detection (20 CFU/mL) through a portable ATP bioluminescent meter. The multifunctional ZIF-90@Luc-AMP biosensor with high stability, specificity, and sensitivity was also appropriate for rapid pathogen screening and antibacterial application in the wild.

An integrated three-signal biosensor based on phage multifunctional probe for simultaneous and ultrasensitive detection of live /dead Listeria monocytogenes

The simultaneous and sensitive detection of live/dead bacteria in food samples is crucial for the control and prevention of foodborne pathogen contamination. Herein, a novel three-signal biosensor for simultaneous and ultrasensitive detection of live/dead Listeria monocytogenes (L.m) was developed. Concretely, a phage/prussian blue nanoparticles (PBNPs) and phage/polyethyleneimine@magnetic nanoparticles (PEI@MNPs) multifunctional probes were prepared. In the presence of L.m, a sandwich complex of phage/PBNPs-L.m-phage/PEI@MNPs was formed and separated by magnetic field. With the lytic activity of phages, the bioluminescent signal generated by adenosine triphosphate (ATP) was utilized for the quantification of live L.m. Photothermal and colorimetric signals triggered by the PBNPs could quantitative determination of total L.m. The combined results of total/live bacteria detection facilitate the calculation of dead bacteria. Bioluminescent signal allows for the precise detection of live L.m with a limit of detection (LOD) of 1 CFU/mL, while the photothermal and colorimetric signals enable on-site measurement of total bacteria with a LOD of 5 CFU/mL. This biosensor exhibits the multiple signals, realizing the diversification of bacterial information output. Meanwhile, the three signals can realize the mutually support, thereby improving the accuracy of detection results. This work opens a new avenue for the simple, ultrasensitive and simultaneous quantification of both live and dead bacteria.

Monolayer-Fluorescence Counting for Ultrasensitive Detection of Tumour Cell-Derived Extracellular Vesicles Using a Step-wedge Microfluidic Platform

Extracellular vesicles have emerged as significant noninvasive tumour biomarkers, and ultrasensitive detection methods are important for early cancer diagnosis. Here, a monolayer-fluorescence counting strategy was developed for the ultrasensitive detection of extracellular vesicles using a microfluidic platform. Extracellular vesicles were specially captured and separated from complex matrix by immune magnetic microbeads (IMBs). With an enhancing acoustic wave microfluidic channel, the magnetic-extracellular vesicles immune complex was adequately mixed and reacted with antibody-modified fluorescence microbeads (IFBs). Using a newly designed step-wedge microfluidic structure, micrometer-size particles were trapped in large numbers with monolayer in the step zone, and the fluidic resistance was reduced through the wedge structure. This detection signal of the fluorescence-labelled immune sandwich complex could be read by counting, avoiding background interference and achieving an ultrasensitive detection with a detection limit of 850 particles/mL. Moreover, this method showed strong reliability and specificity in clinic samples. In addition, a miniaturized detection device was developed based on this microfluidic platform, improving this detection automation.

POD-like nanozyme constructed from perspective of charge transfer engineering for biosensing of magnetic separation treated Listeria monocytogenes

For foodborne pathogens pose a serious threat to public health, a magnetic separation strategy and a nanozyme-based biosensor are proposed for biosensing of Listeria monocytogenes (L. monocytogenes). In this work, doripenem is selected as a recognized molecule for the modification of magnetic beads to capture L.monocytogenes in food and environmental samples. Furthermore, the POD-like MXene-Hemin-Au is constructed from perspective of charge transfer engineering which provides a vivid example to rational design of nanozymes. Finally, the captured L.monocytogenes is labeled with MXene-Hemin-Au@mAb, forming the sandwich complexes for quantitative determination. The current signals that generated by the complexes exhibit a good linear relationship with a limit of detection of 2.3 × 101 CFU/mL. The biosensor shows a satisfactory applicability in real samples with recoveries of 91.19% to 102.98%. Overall, the biosensor with integrated magnetic separation strategy presents a potential approach for high sensitivity biosensing of foodborne pathogens.

Assembled Structures and Electrical Conductivities of Salts Comprised of Cationic Sandwich Complexes and Polyoxometalates.

Polyoxometalates (POMs) are recognized for their diverse structures and catalytic properties, yet their organometallic salts have not been thoroughly investigated. In this study, we synthesized salts of a Keggin-type POM with cationic sandwich complexes featuring various substituents, [X]2[SMo12O40] [X = Ru(C5H5)(C6H5R); R = H (1a), Me (1b), Bu (1c)], [Co(C5H5)2 (2), and Co(C5Me5)2 (3)]. These salts exhibited similar structural characteristics, with each anion surrounded by 10 cations, forming two-dimensional sheet arrangements through O···O anion-anion contacts, except for the salt of 1c, which exhibited one-dimensional contact owing to the larger cation substituent. Additionally, [2](THA)[Mo6O19], [3]2[Mo6O19], and [3](THA)[SMo12O40], containing the Lindqvist-type POM [Mo6O19] and/or tetrahexylammonium (THA) cation, were obtained, with the packing structure of [3]2[Mo6O19] closely resembling that of [X]2[SMo12O40]. Solvate crystals of [1a]3[PMo12O40] were also prepared. [1a]2[SMo12O40] exhibits an electrical conductivity σ of 1.4 × 10-7 S cm-1 at 373 K, which is 2 orders of magnitude higher than those of (THA)2[SMo12O40] and [1a]PF6.

Theoretical Investigation on One-Electron ϕ···ϕ Bonding in Diuranium Inverse Sandwich U2B6 Complex Enabled by a B6 Ring.

Traditional σ, π, and δ types of covalent chemical bonding have been extensively studied for nearly a century. In contrast, ϕ-type bonding involving nf (n = 4, 5) orbitals has received less attention due to their high contraction and minimal orbital overlap. Herein, we theoretically predict a singly occupied ϕ···ϕ bonding between two 5f orbitals, facilitated by B6 group orbitals in the hexa-boron diuranium inverse sandwich structure of U2B6. From ab initio quantum chemical calculations, the global minimum structure has a septuplet state with D6h symmetry. Chemical bonding analyses reveal that the 5f and 6d atomic orbitals of the two uranium atoms interact with the ligand orbitals of the central B6 ring, exhibiting favorable energy matching and symmetry compatibility to form delocalized σ-, π-, δ-, and ϕ-type bonding orbitals. Notably, even though the ϕ···ϕ bonding orbital is singly occupied, it still has a significant role in stability and cannot be overlooked. Furthermore, the U2B6 cluster model can be viewed as a building block of UB2 solid materials from both geometric and electronic perspectives. This work predicts the first example of ϕ···ϕ bonding, highlighting the complexity and diversity of chemical bonds formed in actinide boride clusters.

A Visual Distance-Based Capillary Immunoassay Using Biomimetic Polymer Nanoparticles for Highly Sensitive and Specific C-Reactive Protein Quantification.

The low-cost daily monitoring of C-reactive protein (CRP) levels is crucial for screening acute inflammation or infections as well as managing chronic inflammatory diseases. In this study, we synthesized novel 2-Methacryloyloxy ethyl phosphorylcholine (MPC)-based biomimetic nanoparticles with a large surface area to develop a visual CRP-quantification assay using affordable glass capillaries. The PMPC nanoparticles, synthesized via reflux precipitation polymerization, demonstrated multivalent binding capabilities, enabling rapid and specific CRP capture. In the presence of CRP, PMPC nanoparticles formed sandwich structures with magnetic nanoparticles functionalized with CRP antibodies, thereby enhancing detection sensitivity and specificity. These sandwich complexes were magnetically accumulated into visible and quantifiable stacks within the glass capillaries, allowing for the rapid, sensitive, and specific quantification of CRP concentrations with a detection limit of 57.5 pg/mL and a range spanning from 0 to 5000 ng/mL. The proposed visual distance-based capillary biosensor shows great potential in routine clinical diagnosis as well as point-of-care testing (POCT) in resource-limited settings.

Tracking Noncovalent Interactions of π, π-Hole, and Ion in Molecular Complexes at the Single-Molecule Level.

Noncovalent interactions involving aromatic rings, such as π-stacking and π-ion interactions, play an essential role in molecular recognition, assembly, catalysis, and electronics. However, the inherently weak and complex nature of these interactions has made it challenging to study them experimentally, especially with regard to elucidating their properties in solution. Herein, the noncovalent interactions between π and π-hole, π and cation, and π-hole and anion in molecular complexes in nonpolar solution are investigated in situ through single-molecule electrical measurements in combination with theoretical calculations. Specifically, phenyl and pentafluorobenzyl groups serve as π and π-hole sites, respectively, while Li+ and Cl- are employed as the cation and anion. Our findings reveal that, in comparison with homogeneous π···π interactions, heterogeneous π···π-hole and π···cation interactions exhibit greater binding energies, resulting in a longer binding lifetime of the molecular junctions. Meanwhile, π···Li+ and π-hole···Cl- interactions present significantly distinct binding characteristics, with the former being stronger but more flexible than the latter. Furthermore, by changing the molecular components, similar conductivity can be achieved in both molecular dimers or sandwich complexes. These results provide new insights into π- and π-hole-involved noncovalent interactions, offering novel strategies for precise manipulation of molecular assembly, recognition, and molecular device.

IRTIDP: A simple integrated real-time isolation and detection platform for small extracellular vesicles Glypican-1 in pancreatic cancer patients

Glypican-1 (GPC-1) protein-positive small extracellular vesicles (GPC-1+-sEV) have been proposed as potential biomarkers for early diagnosis of pancreatic cancer. In this study, we present an integrated real-time isolation and detection platform (IRTIDP) to capture and analyze GPC-1+-sEV directly from sera of pancreatic cancer patients. First, CD63 antibody-modified metal-organic framework (MOF) materials were utilized to enrich sEVs with a capture efficiency of 93.93 %. Second, a SERS probe was constructed by Raman reporter 4-MBA and GPC-1 antibody modified SERS active silver nanoparticles (AgNPs), which formed a sandwich complex structure of "MOFs@GPC-1+-sEV@AgNPs-4-MBA" with MOFs-enriched sEVs. The IRTSDP can complete the capture and detection process within 35 min, with a detection limit for 1 GPC-1+-sEV/μL, and linear range between 105∼109 GPC-1+-sEV/mL. Furthermore, this approach has been applied to quantify serum sEV GPC-1 in clinical pancreatic cancer patients. Based on the SERS intensity analysis, pancreatic cancer patients can be distinguished from pancreatic cystadenoma patients and healthy individuals effectively using this innovative platform that provides highly specific and sensitive means for early diagnosis of pancreatic cancer as well as other tumor types.

Bimetallic loaded ZIF-8 with peroxidase-like and photothermal activities for sensitive detection and efficient elimination of Listeria monocytogenes

Listeria monocytogenes is one of the main causes of bacterial infectious diseases, posing a grave threat to food safety and global public health. Therefore, sensitive and accurate detection and efficient elimination of L. monocytogenes to prevent secondary pollution is of great significance and necessary. Herein, a nanocomposite ZIF-8@Au@Pt NPs was synthesized with excellent peroxidase-like (POD) activity, SERS property and photothermal conversion property. ZIF-8@Au@Pt NPs was further cloaked with a specific aptamer (Apt2), thus presenting precise recognition to L. monocytogenes. Magnetic beads with good separation and enrichment effect were modified with another specific aptamer (Apt1), a sandwich complex was then obtained based on the high affinity of aptamers to L. monocytogenes. The supernatant containing unreacted ZIF-8@Au@Pt NPs were capable of oxidizing colorless 3,3′,5,5′-tetramethylbenzidine (TMB) into blue oxTMB in the presence of H2O2, thus enabling colorimetric testing. Meanwhile, the generated oxTMB exhibited a distinct SERS fingerprint, realizing accurate detection of L. monocytogenes through dual-mode (colorimetric and SERS), with respective detection limits of 7 CFU/mL and 5 CFU/mL. Moreover, ZIF-8@Au@Pt NPs demonstrated exceptional photothermal conversion ability (η = 71.72 %) under a near-infrared irradiation. Approaching 100 % bactericidal effect was obtained within 2 min on the precipitates by combining its function of producing reactive oxygen species (ROS) and the near-infrared photothermal property, effectively avoiding secondary pollution. The present study presented a novel approach for realizing sensitive and accurate detection and subsequent eradication of L. monocytogenes.

A dual-mode composite nanozyme-based cascade colorimetric-fluorescence aptasensor for Salmonella Typhimurium detection

BackgroundSalmonella Typhimurium poses a serious threat to human health worldwide, necessitating the development of a rapid, sensitive, and convenient method for S. Typhimurium detection. Nanozymes are considered ideal signal report elements, which are extensively used for developing colorimetric methods. However, single-component nanozymes display low catalytic activity, and colorimetric methods are susceptible to environmental interference, reducing the sensitivity and accuracy of detection results. To address these drawbacks, this study constructed a dual-mode composite nanozyme-based cascade colorimetric-fluorescence aptasensor for S. Typhimurium detection in food. ResultsIn this study, the composite Fe3O4@MIL-100(Fe) nanozymes were successful synthesized and demonstrated substantial peroxide-like activity, with 4.76-fold higher specificity activity (SA) than that of Fe3O4 nanozymes. Then, a glucose oxidase (GOx)-Fe3O4@MIL-100(Fe) cascade reaction was developed for colorimetric detection via an aptamer to facilitate the formation of Fe3O4@MIL-100(Fe)/S. Typhimurium/carboxylated g-C3N4 (CCN)-GOx sandwich complexes. Meanwhile, the fluorescence mode was achieved by measuring the fluorescence intensity of the sandwich complexes. In optimum conditions, the dual-mode detection limits (LOD) were 1.8 CFU/mL (colorimetric mode) and 1.2 CFU/mL (fluorescence mode), respectively, with the S. Typhimurium concentration ranging from 10 CFU/mL to 107 CFU/mL. Finally, the feasibility of the dual-mode colorimetric-fluorescence method was validated via three actual samples, yielding recovery rates of 77.32 % to91.17 % and 82.17 % to 103.7 %, respectively. Significance and noveltyThis study successfully develops a composite nanozyme-based cascade colorimetric and fluorescence dual-mode aptasensor for S. Typhimurium detection. It presents several distinct benefits, such as a broader linear range (10–107 CFU/mL), a lower LOD value (1.2 CFU/mL), and more accurate results. More importantly, the proposed dual-mode method displays a low LOD in colorimetric mode, demonstrating considerable potential for S. Typhimurium on-site detection in food.

Anticancer potential of NSAID-derived tris(pyrazolyl)methane ligands in iron(II) sandwich complexes.

Tris(pyrazolyl)methane (tpm), 2,2,2-tris(pyrazolyl)ethanol (tpmOH) and its esterification derivatives with ibuprofen and flurbiprofen (tpmIBU and tpmFLU) were used as ligands to obtain complexes of the type [Fe(tpmX)2]Cl2 (1-4). The tpmIBU and tpmFLU ligands and corresponding complexes 3 and 4 were characterized by IR and multinuclear NMR spectroscopy, and the structure of tpmIBU was elucidated by single crystal X-ray diffraction. Complexes 1-4 were also assessed for their behaviour in aqueous media (solubility in D2O, octanol/water partition coefficient, stability in physiological-like conditions). The antiproliferative activity of ligands and complexes was determined on A2780, A2780cis and A549 cancer cell lines and the non-cancerous HEK 293T and BJ cell lines. The ligands and complexes were investigated for their ability to inhibit COX-2 (cyclooxygenase) and HNE (4-hydroxynonenal) enzymes. Complexes 3 and 4 exhibited cytotoxicity that may be attributed predominantly to their bioactive fragments, while DNA binding and enhancement of ROS production do not appear to play any significant role.

(Invited) Doping at the Extreme in Organic Semiconductors: Challenges and Opportunities

Molecular doping is an effective tool to enhance bulk conductivity, increase carrier injection and de-activate electron or hole traps in organic molecular and polymer semiconductors. Considerable effort has been directed toward the synthesis of powerful and stable p-type and n-type molecular dopants over the past decade.[1,2] This talk reviews a range of molecular redox agents used in organic electronics, with focus on strong reductants and oxidants for organic semiconductors with low electron affinity (EA) and large ionization energy (IE), respectively. In particular, we look at air-stable dimers, e.g. [RuCp*Mes]2, formed of 19-electron organometallic sandwich compounds able to reduce organic semiconductors with EA well below 3 eV.[3] We review powerful single-electron molecular oxidants, e.g. F6-TCNNQ and CN6-CP, which can introduce holes in organic semiconductors with IE larger than 5.6 eV. Applications of these n- and p-dopants to improve the conductivity of carrier injection layers and create large gap semiconductor p-i-n structures are described.[4] The last part of the talk focuses on recent work on adduct-based p-doping of organic semiconductors, applicable to a range of hole transport materials.[5][1]S. Barlow, S.R. Marder, X. Lin, F. Zhang and A. Kahn, Electrical Doping of Organic Semiconductors with Molecular Oxidants and Reductants, Handbook of Conducting Polymers (2019)[2] G. Song, S.B. Kim,S. Mohapatra, Y. Qi, T. Sajoto, A. Kahn, S.R. Marder, S. Barlow, n-Doping of Organic Electronic Materials Using Air-Stable Organometallics, Adv. Mat. 24, 699 (2012)[3] X. Lin, B. Wegner, K. M. Lee, M. A. Fusella, F. Zhang, K. Moudgil, B. P. Rand, S. Barlow, S. R. Marder, N. Kochand A. Kahn, Beating the Thermodynamic Limit: Photo-Activation of n-Doping in Organic Semiconductors, Nature Materials 16, 1209 (2017)[4] H. L. Smith, J. T. Dull, S. Mohapatra, S. Barlow, S. Marder, B. P. Rand, and A. Kahn, Powerful organic molecular oxidant and reductant enable a large gap, blue light-emitting organic homojunction diode, ACS Appl. Mat. Int. 14, 2381 (2022)[5] N. Sakai, R. Warren, F. Zhang, S. Nayak, S. V. Kesava, Y.-H. Lin, H. S. Biswal, X. Lin, A. Kahn, M. Riede, P. K. Nayak and H. J. Snaith, Adduct-based p-doping of Organic Semiconductors, Nature Materials, 20, 1248 (2021)

Rare earth mixed sandwich complexes with tetraalkylphospholide and cyclooctatetraenide ligands

A series of rare earth (mono)phospholide mixed sandwich complexes of the general form [M(PC4R4)(COT)(THF)n] (M = Sc, Y, La, Lu; R = Me, Et; COT = cyclooctatetraenide, {C8H8}2–; n = 0 to 2) have been isolated by the treatment of iodide precursors, [M(COT)(I)(THF)n], (1M, M = Sc, Y, Lu, n = 2; M = La, n = 3) with potassium phospholide salts, [K(PC4R4)]n (R = Me, Et). The solid-state molecular structures and speciation of these sandwich complexes depends upon both the ionic radius of the rare earth metal, along with small steric and solubility differences which arise between the two per-alkylated phospholide ligands. The smaller {PC4Me4} ligand gave monomeric Lewis-base free [M(C8H8)(PC4Me4)] (2M, M = Sc, Lu) with smaller rare earths Sc(III) and Lu(III), but moving to larger ions Y(III) and La(III), the products were poorly soluble and could only be isolated as THF-adducts, [Y(C8H8)(PC4Me4)(THF)] (3) and [La(C8H8)(PC4Me4)(THF)2] (4). The slightly increased steric demands of {PC4Et4} gave monomeric Lewis-base free complexes for Sc(III), Lu(III), and Y(III) in [M(C8H8)(PC4Et4)] (5M, M = Sc, Y, Lu), whereas for La(III) a dimeric complex was isolated, [La(C8H8)(µ-PC4Et4)]2 (6). We also report the synthesis and molecular structures of 1Sc and 1Lu, as well as [LuI3(THF)3] (7) for the first time. All complexes were characterised by single crystal X-ray diffraction, multi-nuclear NMR, UV-Vis-NIR and ATR-IR spectroscopies in addition to elemental analysis.