SLAM Family Receptors in B Cell Chronic Lymphoproliferative Disorders.

The signaling lymphocytic activation molecule (SLAM) receptor family (SLAMF) consists of nine glycoproteins that belong to the CD2 superfamily of immunoglobulin (Ig) domain-containing molecules. SLAMF receptors modulate the differentiation and activation of a wide range of immune cells. Individual SLAMF receptors are expressed on the surface of hematopoietic stem cells, hematopoietic progenitor cells, B cells, T cells, NK cells, NKT cells, monocytes, macrophages, dendritic cells, neutrophils, and platelets. The expression of SLAMF receptors was studied during normal B cell maturation. Several SLAMF receptors were also detected in cancer cell lines of B-lymphoid origin and in pathological B cells from patients with B cell chronic lymphoproliferative disorders (B-CLPD), the most frequent hematological malignancies in adults. This review summarizes current knowledge on the expression of SLAMF receptors and their adaptor proteins SAP and EAT-2 in B-CLPD. Several SLAMF receptors could be regarded as potential diagnostic and differential diagnostic markers, prognostic factors, and targets for the development of novel drugs for patients with B-CLPD.

A Rare Early-Onset Fatal Complication after Transarterial Chemoembolization: A Case Report and Review of the Literature.

Transarterial chemoembolization (TACE) is a minimally invasive treatment for liver cancer, often employed as a bridging therapy or destination treatment for non-operable cases. This case report discusses an 82-year-old woman with a large hepatocellular carcinoma (HCC) who underwent elective TACE due to the high surgical risk associated with her tumor size. Unexpectedly, the patient experienced liver rupture 20 h post-procedure, leading to acute surgical intervention. Despite successful hemostasis during surgery, the patient succumbed to progressive multi-organ failure. We aimed to search the PubMed database for documented cases of ruptured HCC after TACE. This study highlights risk factors for spontaneous HCC rupture and specific factors associated with TACE-induced rupture. Transarterial embolization (TAE) is currently favored as the treatment method for spontaneous ruptures, while the optimal therapy for TACE-induced ruptures remains unclear. In conclusion, this case underscores the importance of recognizing the rare complication of HCC rupture post-TACE and the need for personalized risk assessment. While TAE emerges as a primary treatment choice, the lack of consensus necessitates further studies to establish evidence-based approaches for managing this uncommon yet life-threatening complication.

Positive matrix factorization of seasonally resolved organic aerosol at three different central European background sites based on nuclear magnetic resonance Aerosolomics data.

Concentration data derived from 1H NMR analysis of the water-soluble organic compounds from fine aerosol (PM2.5) at three Central European background stations, Kosetice, Frýdlant (both in the Czech Republic), and Melpitz (Germany), were used for detailed source apportionment analysis. Two winter and two summer episodes (year 2021) with higher organic concentrations and similar wind directions were selected for NMR analyses. The concentration profiles of 61 water-soluble organic compounds were determined by NMR Aerosolomics and a principal component analysis (PCA) was performed on this dataset. Based on the PCA results, 23 compounds were selected for positive matrix factorization (PMF) analysis in order to identify dominant aerosol sources at rural background sites in Central Europe. Both the PCA and the subsequent PMF analyses clearly distinguished the characteristics of winter and summer aerosol particles. In summer, four factors were identified from PMF and were associated with biogenic aerosol (61-78 %), background aerosol (9-15 %), industrial biomass combustion (7-13 %), and residential heating (5-13 %). In winter, only 3 factors were identified - industrial biomass combustion (33-49 %), residential heating (37-45 %) and a background aerosol (8-30 %). The main difference was observed in the winter season with a stronger contribution of emissions from industrial biomass burning at the Czech stations Kosetice and Frýdlant (47-49 %) compared to the Melpitz station (33 %). However, in general, there were negligible differences in identified sources between stations in the given seasons, indicating a certain homogeneity in PM2.5 composition within Central Europe at least during the sampling periods.

Impact of autologous stem cell transplantation (ASCT) on progression free survival (PFS) in newly diagnosed multiple myeloma patients (NDMM) with high risk cytogenetic abnormalities.

OBJECTIVES: ASCT has been considered the standard of care for younger patients with NDMM, however, not all the studies published so far have uniformly demonstrated the complete superiority of ASCT over chemotherapy at standard doses. A systematic review and meta-analysis of randomized studies has shown a significant benefit with single ASCT in terms of prolonged progression-free survival (PFS), but not of overall survival (OS). In our retrospective analysis we investigated the impact of high dose (HD) chemotherapy followed by ASCT in special population of patients with high risk cytogenetic profile on the PFS and treatment outcome. METHODS: Retrospective analysis of NDMM patients eligible for HD chemotherapy followed by upfront ASCT in the era of novel agents, who underwent the ASCT in the Department of hematology and oncohematology LF UPJS and UNLP Kosice in the timeframe of 54 months (from 01/JAN/2019 to 30/JUN/2023). Patients were stratified according to their cytogenetic profile. PFS was defined by the time from ASCT to the disease progression. The OS was defined as the time from the the start of treatment to the death from disease progression. The high risk cytogenetic abnormalities (HRCA) were defined as t(4;14), del(17/17p), t(14;16), t(14;20), nonhyperploidy, gain (1q). RESULTS: Inclusion criteria were met by 65 patients with NDMM who received HD chemotherpy followed by ASCT. We identified 22 (33.8 %) patients with HRCA and 43 (66.2 %) patients with standard cytogenetic risk. During the monitored period we recorded 4 deaths due to disease progression, all of them in the HCRA subgroup. The response was enhanced by the ASCT in both subgroups. The very good partial response (VGPR) increased from 42 % to 46 % and complete remission (CR) increased from 23 % to 45 % after the ASCT. The number of patients achieving only partial response (PR) decreased from 35 % to 9 % after ASCT. In the subgroup of patients with HRCA the median PFS after ASCT was lower compared to the patients with standard cytogenetic risk (17 vs 38 months). The average PFS in both subgroups was 22.9 months. The median OS in both subgroups was not reached, however the only deaths due to disease progression were recorded in the HRCA subgroup. At the time of analysis, 100 % (43) of patients are alive in the standard cytogenetic subgroup versus 72 % (18) of patients in HRCA subgroup. CONCLUSION: HD chemotherapy followed by ASCT remains the standard of care for NDMM eligible for high dose chemotherapy. Our results confirm the benefit of ASCT even in the presence of HRCA. Lower PFS in the HRCA subgroup might indicate the need for more intensive treatment, which may be achieved by tandem ASCT defined as two ASCT performed within a period of no more than six months. Additionally, as three- and four-drug induction therapies are becoming increasingly available and effective, resulting in high minimal residual disease (MRD) negative rates, it is important to continue discussing and further personalizing upfront ASCT to avoid overtreatment and possible toxicities especially in the non-high-risk patient population (Tab. 5, Fig. 2, Ref. 9).

The role of computed tomography pulmonary angiography in COVID-19 patients with suspected pulmonary embolism.

OBJECTIVES: This study is aimed to determine the location and distribution of pulmonary embolism (PE) and presence of signs potentially indicative of right heart overload on computed tomography pulmonary angiography (CTPA) in COVID-19 and non-COVID-19 patients. We also evaluated the extent and severity of COVID-19-associated lung changes in relation to PE. METHODS: The total number of 1,698 patients with CTPA included in the study were divided into 2 groups according to their COVID-19 status and each group was divided into 2 subgroups based on their PE status. These groups and subgroups were compared in terms of location of PE, diameter of pulmonary artery, right heart strain, ground-glass opacities (GGO), consolidations and other imaging features. RESULTS: In COVID-19 patients, there was a significant predominance of PE in peripheral branches of pulmonary artery (p < 0.001). There was an increased right-to-left ratio of ventricular diameters in cases with PE (p = 0.032 in patients with COVID-19 and p < 0.001 in non-COVID-19 patients). There was no association between the extent and severity of the disease and distribution of PE. CONCLUSION: COVID-19 is associated with a higher incidence of peripheral location of PE and presence of GGO. There were signs indicative of right heart overload in cases with PE regardless of COVID-19 (Tab. 3, Fig. 1, Ref. 29) Keywords: COVID-19, computed tomography, CTPA, pneumonia, pulmonary embolism.

Association between pulmonary embolism and COVID-19 disease.

OBJECTIVES: The current retrospective study focused on evaluation of the relationship between pulmonary embolism during COVID-19 pandemic and demographic, presenting symptoms, comorbidities and laboratory results in patients who underwent CT angiography of the pulmonary arteries. METHODS: The study enrolled all adult patients with suspected acute pulmonary embolism (PE) who underwent computed tomography pulmonary angiography (CTPA) between March 1, 2020, and April 30, 2022, during the SARS-CoV-2 pandemic. 1698 CTPAs were reviewed and various data were collected. Based on examination results, patients were divided into 4 groups: a group with positive PE and a group with negative PE for both COVID-19 and non-COVID-19 patients. RESULTS: When comparing different predictors of COVID-19 patients and non-COVID-19 patients we noticed lower probability of PE in female gender (OR 0.77, 95% CI: 0.60-1.00, p = 0.052) and in chronic obstructive pulmonary disease (COPD) patients (OR 0.6, 95% CI: 0.38-0.90, p = 0.017). Higher probability of PE was in cases of older age (OR 1.02, 95% CI: 1.01-1.02, p < 0.001), increased heart rate (OR 1.01, 95% CI: 1.01-1.02, p < 0.001) and increased D-dimer levels (OR 1.03, 95% CI: 1.02-1.04, p < 0.001). CONCLUSION: Considering predictors of PE there was a significantly lower risk of PE in the female gender and COPD, and a higher risk with increasing age, heart rate, and D-dimer levels.

Prediction of Pathologic Change Development in the Pancreas Associated with Diabetes Mellitus Assessed by NMR Metabolomics.

Nuclear magnetic resonance (NMR) metabolomics was used for identification of metabolic changes in pancreatic cancer (PC) blood plasma samples when compared to healthy controls or diabetes mellitus patients. An increased number of PC samples enabled a subdivision of the group according to individual PC stages and the construction of predictive models for finer classification of at-risk individuals recruited from patients with recently diagnosed diabetes mellitus. High-performance values of orthogonal partial least squares (OPLS) discriminant analysis were found for discrimination between individual PC stages and both control groups. The discrimination between early and metastatic stages was achieved with only 71.5% accuracy. A predictive model based on discriminant analyses between individual PC stages and the diabetes mellitus group identified 12 individuals out of 59 as at-risk of development of pathological changes in the pancreas, and four of them were classified as at moderate risk.

Chiral Light Emission from a Hybrid Magnetic Molecule-Monolayer Transition Metal Dichalcogenide Heterostructure.

Hybrid layered materials assembled from atomically thin crystals and small molecules bring great promises in pushing the current information and quantum technologies beyond the frontiers. We demonstrate here a class of layered valley-spin hybrid (VSH) materials composed of a monolayer two-dimensional (2D) semiconductor and double-decker single molecule magnets (SMMs). We have materialized a VSH prototype by thermal evaporation of terbium bis-phthalocyanine onto a MoS2 monolayer and revealed its composition and stability by both microscopic and spectroscopic probes. The interaction of the VSH components gives rise to the intersystem crossing of the photogenerated carriers and moderate p-doping of the MoS2 monolayer, as corroborated by the density functional theory calculations. We further explored the valley contrast by helicity-resolved photoluminescence (PL) microspectroscopy carried out down to liquid helium temperatures and in the presence of the external magnetic field. The most striking feature of the VSH is the enhanced A exciton-related valley emission observed at the out-of-resonance condition at room temperature, which we elucidated by the proposed nonradiative energy drain transfer mechanism. Our study thus demonstrates the experimental feasibility and great promises of the ultrathin VSH materials with chiral light emission, operable by physical fields for emerging opto-spintronic, valleytronic, and quantum information concepts.

Modulation of Anionic Lipid Bilayers by Specific Interplay of Protons and Calcium Ions.

Biomembranes, important building blocks of living organisms, are often exposed to large local fluctuations of pH and ionic strength. To capture changes in the membrane organization under such harsh conditions, we investigated the mobility and hydration of zwitterionic and anionic lipid bilayers upon elevated H3O+ and Ca2+ content by the time-dependent fluorescence shift (TDFS) technique. While the zwitterionic bilayers remain inert to lower pH and increased calcium concentrations, anionic membranes are responsive. Specifically, both bilayers enriched in phosphatidylserine (PS) and phosphatidylglycerol (PG) become dehydrated and rigidified at pH 4.0 compared to at pH 7.0. However, their reaction to the gradual Ca2+ increase in the acidic environment differs. While the PG bilayers exhibit strong rehydration and mild loosening of the carbonyl region, restoring membrane properties to those observed at pH 7.0, the PS bilayers remain dehydrated with minor bilayer stiffening. Molecular dynamics (MD) simulations support the strong binding of H3O+ to both PS and PG. Compared to PS, PG exhibits a weaker binding of Ca2+ also at a low pH.

Dissecting the mechanisms of environment sensitivity of smart probes for quantitative assessment of membrane properties.

The plasma membrane, as a highly complex cell organelle, serves as a crucial platform for a multitude of cellular processes. Its collective biophysical properties are largely determined by the structural diversity of the different lipid species it accommodates. Therefore, a detailed investigation of biophysical properties of the plasma membrane is of utmost importance for a comprehensive understanding of biological processes occurring therein. During the past two decades, several environment-sensitive probes have been developed and become popular tools to investigate membrane properties. Although these probes are assumed to report on membrane order in similar ways, their individual mechanisms remain to be elucidated. In this study, using model membrane systems, we characterized the probes Pro12A, NR12S and NR12A in depth and examined their sensitivity to parameters with potential biological implications, such as the degree of lipid saturation, double bond position and configuration (cis versus trans), phospholipid headgroup and cholesterol content. Applying spectral imaging together with atomistic molecular dynamics simulations and time-dependent fluorescent shift analyses, we unravelled individual sensitivities of these probes to different biophysical properties, their distinct localizations and specific relaxation processes in membranes. Overall, Pro12A, NR12S and NR12A serve together as a toolbox with a wide range of applications allowing to select the most appropriate probe for each specific research question.

Comparison of Restenosis Risk in Single-Layer versus Dual-Layer Carotid Stents: A Duplex Ultrasound Evaluation.

PURPOSE: The aim of this study was to report intermediate-term results of duplex ultrasound follow-up of carotid artery stenting performed with the dual-layer stent as compared to concurrent patients treated with other commercially available single-layer carotid stents. MATERIALS AND METHODS: A single centre, retrospective, nonrandomized study including 162 non-consecutive patients with 199 implanted carotid stents treated over a 7-year period was conducted. Patients with at least one ultrasound examination after treatment were included. Procedural and follow-up data for patients treated with the dual-layer stent implantation (83 stents) vs first-generation carotid stents implantations (116 stents) were compared. RESULTS: The median follow-up time was 24.0 months (IQR 10-32 months) for dual-layer stents and 27.5 months (IQR 10.3-59 months) for single-layer stents. The rate of severe restenosis was significantly higher in the dual-layer stent group than in the single-layer group (13.3% [11/83] vs 3.4% [4/116], p = 0.01). Seven reinterventions were performed in 5 patients with dual-layer stents. The rate of reintervention was significantly higher compared to no reinterventions in single-layer stents (6% [5/83] vs 0% [0/116], p = 0.012). Patients with restenosis had significantly higher presence of dyslipidaemia (100% [12/12] vs 63.3% [95/150], p = 0.009). CONCLUSIONS: In this real-world cohort of patients undergoing carotid artery stenting, the patients treated with low-profile dual-layer micromesh stent showed higher rates of restenosis and reinterventions compared to first-generation single-layer stents.

Synthesis of 2-Phospha[7]helicene, a Helicene with a Terminal Phosphinine Ring.

A synthetic strategy toward phosphahelicenes containing a terminal phosphinine ring has been explored. The 4-phenyl-6-methyl-2-phospha[7]helicene was prepared from starting 2-bromobenzo[c]phenanthrene in 12% overall yield in 12 steps. The synthetic approach involves introduction of the phosphorus function prior to photocyclization forming the final helicene skeleton, followed by the formation of a phosphorus hexacycle. The structure of the first phosphahelicene with a terminal phosphinine ring was confirmed by X-ray crystallography.

Synthesis of Aza[n]helicenes (n = 4-7) via Photocyclodehydrochlorination of 1-Chloro-N-aryl-2-naphthamides.

A series of aza[n]helicenes (n = 4-7) was synthesized using a photocyclodehydrochlorination of 1-chloro-N-aryl-2-naphthamides as a general synthetic procedure introducing the nitrogen atom to the third ring of the helicene framework. The effect of the nitrogen presence in the helicene skeleton on the physicochemical properties of the prepared aza[n]helicenes was studied and compared to those of the parent carbo-analogues. The insertion of a nitrogen atom into the outer edge of the helicene molecule has a severe impact on certain physicochemical properties such as optical rotation, electrostatic potentials, and intermolecular interactions. On the other hand, some other properties such as UV/vis, fluorescence, and phosphorescence spectra remained almost unaffected when compared to the parent carbohelicenes. A nitrogen atom can be also used for further derivatization, which can lead to further modification of helicene properties, as manifested here in the fluorescence changes induced by protonation.

Endovascular Treatment of Gastrointestinal Hemorrhage.

Background and Objectives: Severe non-variceal gastrointestinal bleeding is a life-threatening condition with complicated treatment if endoscopic therapy fails. In such cases, transcatheter arterial embolization is recommended. The technical and clinical effects of this technique were analyzed in this group of patients, as well as its complication rate and 30-day mortality. Materials and Methods: Patient data over a one-decade period (from 2010 to 2019) were analyzed retrospectively; 27 patients (18 men and 9 women; median age 61 years) treated by endovascular embolization in our institution, with clinically significant gastrointestinal hemorrhage after unsuccessful or impossible endoscopic treatment, were identified, and their data were collected. Results: The source of bleeding was found in 88% of patients, but embolization was performed in 96% of them. The overall technical success rate was 96.8%, and the clinical success was 88.5%. Re-bleeding occurred in eight cases, five of whom had re-embolization that was technically successful in four cases. The incidence of re-bleeding was significantly higher in patients with two or more comorbidities (p = 0.043). There was one serious complication (4%) in the group, and minor difficulties occurred in 18% of patients; 30-day mortality reached 22%. Mortality was significantly higher in the group of patients with re-bleeding (p = 0.044). Conclusions: Transcatheter arterial embolization is a mini-invasive method with high technical success in patients with endoscopically untreatable gastrointestinal bleeding; it is also suitable for high-risk cases. Mortality (to a significant extent) depends on the occurrence of re-bleeding and the patient's comorbidities.

The Effect of Deoxyfluorination on Intermolecular Interactions in the Crystal Structures of 1,6-Anhydro-2,3-epimino-hexopyranoses.

The effect of substitution on intermolecular interactions was investigated in a series of 1,6-anhydro-2,3-epimino-hexopyranoses. The study focused on the qualitative evaluation of intermolecular interactions using DFT calculations and the comparison of molecular arrangements in the crystal lattice. Altogether, ten crystal structures were compared, including two structures of C4-deoxygenated, four C4-deoxyfluorinated and four parent epimino pyranoses. It was found that the substitution of the original hydroxy group by hydrogen or fluorine leads to a weakening of the intermolecular interaction by approximately 4 kcal/mol. The strength of the intermolecular interactions was found to be in the following descending order: hydrogen bonding of hydroxy groups, hydrogen bonding of the amino group, interactions with fluorine and weak electrostatic interactions. The intermolecular interactions that involved fluorine atom were rather weak; however, they were often supported by other weak interactions. The fluorine atom was not able to substitute the role of the hydroxy group in molecular packing and the fluorine atoms interacted only weakly with the hydrogen atoms located at electropositive regions of the carbohydrate molecules. However, the fluorine interaction was not restricted to a single molecule but was spread over at least three other molecules. This feature is a base for similar molecule arrangements in the structures of related compounds, as we found for the C4-Fax and C4-Feq epimines presented here.

Solvent-Dependent Excited-State Evolution of Prodan Dyes.

Excited-state character and dynamics of two 6-(dimethylamino)-2-acylnaphthalene dyes (Prodan and Badan-SCH2CH2OH) were studied by picosecond time-resolved IR spectroscopy (TRIR) in solvents of different polarity and relaxation times: hexane, CD3OD, and glycerol-d8. In all these solvents, near-UV excitation initially produced the same S1(ππ*) excited state characterized by a broad TRIR signal. A very fast decay (3, ∼100 ps) followed in hexane, whereas conversion to a distinct IR spectrum with a ν(C═O) band downshifted by 76 cm-1 occurred in polar/H-bonding solvents, slowing down on going from CD3OD (1, 23 ps) to glycerol-d8 (5.5, 51, 330 ps). The final relaxed excited state was assigned as planar Me2N → C═O intramolecular charge transfer S1(ICT) by comparing experimental and TDDFT-calculated spectra. TRIR conversion kinetics are comparable to those of early stages of multiexponential fluorescence decay and dynamic fluorescence red-shift. This work presents a strong evidence that Prodan-type dyes undergo solvation-driven charge separation in their S1 state, which is responsible for the dynamic fluorescence Stokes shift observed in polar/H-bonding solvents. The time evolution of the optically prepared S1(ππ*) state to the S1(ICT) final state reflects environment relaxation and solvation dynamics. This finding rationalizes the widespread use of Prodan-type dyes as probes of environment dynamics and polarity.

What Does Time-Dependent Fluorescence Shift (TDFS) in Biomembranes (and Proteins) Report on?

The organization of biomolecules and bioassemblies is highly governed by the nature and extent of their interactions with water. These interactions are of high intricacy and a broad range of methods based on various principles have been introduced to characterize them. As these methods view the hydration phenomena differently (e.g., in terms of time and length scales), a detailed insight in each particular technique is to promote the overall understanding of the stunning "hydration world." In this prospective mini-review we therefore critically examine time-dependent fluorescence shift (TDFS)-an experimental method with a high potential for studying the hydration in the biological systems. We demonstrate that TDFS is very useful especially for phospholipid bilayers for mapping the interfacial region formed by the hydrated lipid headgroups. TDFS, when properly applied, reports on the degree of hydration and mobility of the hydrated phospholipid segments in the close vicinity of the fluorophore embedded in the bilayer. Here, the interpretation of the recorded TDFS parameters are thoroughly discussed, also in the context of the findings obtained by other experimental techniques addressing the hydration phenomena (e.g., molecular dynamics simulations, NMR spectroscopy, scattering techniques, etc.). The differences in the interpretations of TDFS outputs between phospholipid biomembranes and proteins are also addressed. Additionally, prerequisites for the successful TDFS application are presented (i.e., the proper choice of fluorescence dye for TDFS studies, and TDFS instrumentation). Finally, the effects of ions and oxidized phospholipids on the bilayer organization and headgroup packing viewed from TDFS perspective are presented as application examples.

Synthesis of Aza[n]phenacenes (n = 4-6) via Photocyclodehydrochlorination of 2-Chloro-N-aryl-1-naphthamides.

A novel methodology for the synthesis of aza[n]phenacenes was successfully developed utilizing photocyclodehydrochlorination reaction of 2-chloro-N-aryl-1-naphthamides. In these key intermediates, the factors influencing the photoreaction were studied. The target aza[n]phenacenes were obtained by triflation or chlorination from prepared phenanthridinones, followed by hydrogenation. The introduction of a nitrogen atom into a phenacene skeleton induced changes in the physicochemical properties. The important properties of prepared aza[n]phenacenes (n = 4-6) were studied experimentally and by density functional theory calculations and were compared to those of their carbo analogues. Furthermore, some important features of the crystalline aza[n]phenacenes were investigated, including intermolecular interaction in the crystal lattice and the increased solubility or decreased melting points.

Percutaneous thrombectomy in the management of early rethrombosis in venous thoracic outlet syndrome: two case reports.

BACKGROUND: Venous thoracic outlet syndrome resulting in the upper limb deep venous thrombosis is known as Paget-Schroetter syndrome or effort thrombosis. A general treatment algorithm includes catheter-directed thrombolysis followed by surgical thoracic outlet decompression. There are limited data regarding endovascular treatment of rethrombosis presenting early after the surgery. CASE PRESENTATION: Two cases of early rethrombosis successfully treated with percutaneous mechanical thrombectomy by two different techniques are described. In both cases, rethrombosis was diagnosed soon after thrombolysis and first rib resection with scalenectomy. After 12 months, both patients remain symptom-free, with patent subclavian veins confirmed by duplex ultrasonography. CONCLUSION: Percutaneous mechanical thrombectomy devices may offer a safe treatment option for patients with recurrent thrombosis after thoracic outlet surgery, even when thrombolytic therapy is contraindicated.

Enantioenriched Ruthenium-Tris-Bipyridine Complexes Bearing One Helical Bipyridine Ligand: Access to Fused Multihelicenic Systems and Chiroptical Redox Switches.

The synthesis and photophysical and chiroptical properties of novel aza[n]helicenes (6a-d, 10a,b, n = 4-7) substituted with one or two 2-pyridyl groups are described. The preparation was performed via an adapted Mallory reaction using aromatic imines as precursors. The obtained novel class of helical 2,2'-bipyridine ligands was then coordinated to Ru(bipy)22+ units, thus affording the first diastereomerically and enantiomerically pure [RuL(bipy)2]2+ (11a,c, L = 6a,c) or [Ru2L'(bipy)4]4+ (12, L' = 10b) complexes. The topology and stereochemistry of these novel metal-based helical architectures were studied in detail, notably using X-ray crystallography. Interestingly, the coordination to ruthenium(II) enabled the preparation of fused multihelical systems incorporating aza- and ruthena-helicenes within the same scaffold. The photophysical, chiroptical, and redox properties of these complexes were examined in detail, and efficient redox-triggered chiroptical switching activity was evidenced.