Carotid Cavernous Fistula as a Rare and Late Complication of Maxillofacial Injury: A Brief Clinical Study.

Carotid- Cavernous Fistula (CCF) represents an aberrant vascular communication at the skull base between the high-flow carotid arterial system and the low-flow venous channels within the cavernous sinuses of the sphenoid bone. Benjamin Travers, in the year 1809, described this condition as "pulsating exophthalmos". This case is a presentation of a carotid cavernous fistula in an operated case of maxillofacial injury as a late complication. The individual presented with a nonresolving proptosis and chemosis for the past 9 weeks. This presentation enumerates how the diagnosis was made, though being a rare complication and how it was promptly managed that resulted in a remarkable resolution of signs and symptoms.

Oral Plasmablastic Lymphoma: A Rare Manifestation of HIV-Related Neoplasm-A Brief Clinical Study.

Plasmablastic lymphoma (PBL) is an uncommon and aggressive large B-cell lymphoma commonly diagnosed in human immunodeficiency virus-positive patients. Though the oral cavity is a common site for PBL, this condition is not commonly reported in the literature as an oral manifestation. Most oral PBLs presented as an asymptomatic swelling, frequently associated with ulcerations and bleeding. No standard treatment is yet advocated for oral PBL. Five-year survival rate was recorded not more than 33.5%. This presentation emphasizes on oral manifestation of plasmablastic lymphoma (PBL) as a rare entity, which was provisionally diagnosed for carcinoma (CA) oral cavity. A simple presentation of ulcerated growth in the upper jaw was excised for histopathologic evaluation. Subsequently, it turned out to be a rare oral manifestation of HIV-related lymphoma. It is imperative to understand simple oral presentation as a manifestation of an underlying systemic condition. With this interest, this case presentation is published with a literature review.

Divinylanthracene-Containing Tetracationic Organic Cyclophane with Near-Infrared Photoluminescence.

Near-infrared (NIR) light is known to have outstanding optical penetration in biological tissues and to be non-invasive to cells compared with visible light. These characteristics make NIR-specific light optimal for numerous biological applications, such as the sensing of biomolecules or in theranostics. Over the years, significant progress has been achieved in the synthesis of fluorescent cyclophanes for sensing, bioimaging, and making optoelectronic materials. The preparation of NIR-emissive porphyrin-free cyclophanes is, however, still challenging. In an attempt for fluorescence emissions to reach into the NIR spectral region, employing organic tetracationic cyclophanes, we have inserted two 9,10-divinylanthracene units between two of the pyridinium units in cyclobis(paraquat-p-phenylene). Steady-state absorption, fluorescence, and transient-absorption spectroscopies reveal the deep-red and NIR photoluminescence of this cyclophane. This tetracationic cyclophane is highly soluble in water and has been employed successfully as a probe for live-cell imaging in a breast cancer cell line (MCF-7).

Triplet-Triplet Annihilation Upconversion in a Porphyrinic Molecular Container.

Triplet-triplet annihilation-based molecular photon upconversion (TTA-UC) is a photophysical phenomenon that can yield high-energy emitting photons from low-energy incident light. TTA-UC is believed to fuse two triplet excitons into a singlet exciton through several consecutive energy-conversion processes. When organic aromatic dyes─i.e., sensitizers and annihilators─are used in TTA-UC, intermolecular distances, as well as relative orientations between the two chromophores, are important in an attempt to attain high upconversion efficiencies. Herein, we demonstrate a host-guest strategy─e.g., a cage-like molecular container incorporating two porphyrinic sensitizers and encapsulating two perylene emitters inside its cavity─to harness photon upconversion. Central to this design is tailoring the cavity size (9.6-10.4 Å) of the molecular container so that it can host two annihilators with a suitable [π···π] distance (3.2-3.5 Å). The formation of a complex with a host:guest ratio of 1:2 between a porphyrinic molecular container and perylene was confirmed by NMR spectroscopy, mass spectrometry, and isothermal titration calorimetry (ITC) as well as by DFT calculations. We have obtained TTA-UC yielding blue emission at 470 nm when the complex is excited with low-energy photons. This proof-of-concept demonstrates that TTA-UC can take place in one supermolecule by bringing together the sensitizers and annihilators. Our investigations open up some new opportunities for addressing several issues associated with supramolecular photon upconversion, such as sample concentrations, molecular aggregation, and penetration depths, which have relevance to biological imaging applications.

Surgical Challenges in the Management of Post COVID-19 Midface Mucormycosis (PCoMM): An Institutional Protocol.

BACKGROUND: The coronavirus disease 2019 (COVID-19) pandemic has posed another serious threat, mucormycosis infection, affecting the maxilla and orbitocerebral region. This condition has not spared world population from its merciless claws. This article addresses the challenges faced by the maxillofacial surgeons in setting the protocols from preoperative diagnosis, surgical management to postoperative care, including short-term and long-term rehabilitation. To manage this relentlessly progressing condition, a multispecialty team approach is to be activated in diagnosing, managing, and rehabilitating the patients. PURPOSE: The purpose of this clinical study is to document and analyze the clinical and demographic data, presentation of the lesion, the diagnostic methods followed for early clinical detection, and management of post COVID-19 midface mucormycosis. The article also discusses postoperative medical management and prosthetic rehabilitation. RESULTS: Most of the mucormycosis cases reporting to our center were treated and recovered patients of Severe Acute Respiratory Syndrome Coronavirus 2 infection. Thirty-four (n=34) case were operated for post COVID-19 midface mucormycosis between October 2020 and December 2021. Male to Female ratio is 1:42. The average age of the patients was 57.5 years. Maximum patients were in fifth and sixth decade of life. Maxilla was the involved bone. Treatment was primarily surgical debridement to extended or radical maxillectomy. All patients were treated with Liposomal Amphotericin B and tab posaconazole for 3 to 4 weeks depending upon the age, weight, and physiological state of the patients to attain an optimal cumulative load. Three patients succumbed to illness postoperatively (n=3, 1.02%). Average duration of hospital stay was 47 days. The average review period was 5.1 months.

Fluorescent cyclophanes and their applications.

With the serendipitous discovery of crown ethers by Pedersen more than half a century ago and the subsequent introduction of host-guest chemistry and supramolecular chemistry by Cram and Lehn, respectively, followed by the design and synthesis of wholly synthetic cyclophanes-in particular, fluorescent cyclophanes, having rich structural characteristics and functions-have been the focus of considerable research activity during the past few decades. Cyclophanes with remarkable emissive properties have been investigated continuously over the years and employed in numerous applications across the field of science and technology. In this Review, we feature the recent developments in the chemistry of fluorescent cyclophanes, along with their design and synthesis. Their host-guest chemistry and applications related to their structure and properties are highlighted.

Helically Chiral Hybrid Cyclodextrin Metal-Organic Framework Exhibiting Circularly Polarized Luminescence.

Three achiral polycyclic aromatic fluorophores─namely, 1-pyrenecarboxylic acid, 9-anthracenecarboxylic acid, and perylene-3,9-dicarboxylic acid─were chosen based on their desired properties before being incorporated into the construction of a K+-carrying gamma-cyclodextrin (γ-CD)-based metal-organic framework (CD-MOF-1) and γ-CD-containing hybrid frameworks (CD-HFs). Among these fluorophores, only the pyrene-carrying one shows significant noncovalent bonding interactions with γ-CD in solution. This fluorophore is encapsulated in a CD-HF with a trigonal superstructure instead of the common cubic CD-MOF-1 found in the case of the other two fluorophores. Single-crystal X-ray diffraction analysis of the trigonal CD-HF reveals a π-stacked chiral positioning of the pyrene-carrying fluorophore inside the (γ-CD)2 tunnels and held uniformly around an enantiomorphous 32 screw axis along the c direction in the solid-state structure. This helix-like structure demonstrates an additional level of chirality over and above the point-chiral stereogenic centers of γ-CD and the axial chirality associated with the self-assembled π-stacked fluorophores. These arrangements result in specifically generated photophysical and chiroptical properties, such as the controlled emergence of circularly polarized luminescence (CPL) emission. In this manner, a complete understanding of the mechanism of chirality transfer from a chiral host (CD-HF) to an encapsulated achiral fluorophore has been achieved, an attribute which is often missing in the development of materials with CPL.

Cyclodextrin Metal-Organic Frameworks and Their Applications.

Cyclodextrin-based metal-organic frameworks (CD-MOFs), derived from γ-cyclodextrin (γ-CD) and alkali metal cations, constitute a class of porous, renewable, and edible MOFs that can be synthesized from a naturally occurring carbohydrate on a large scale. γ-CD is a C8-symmetrical cyclic oligosaccharide composed of eight asymmetric α-1,4-linked d-glucopyranosyl residues that possesses a bucket-shaped cavity with an inner diameter of ∼1 nm and a depth of ∼0.8 nm. Upon combination of 1 equiv of γ-CD with 8 equiv of potassium hydroxide in an aqueous solution, followed by vapor diffusion of MeOH (or EtOH) into this solution during several days, CD-MOF-1 is obtained as cubic crystals. This carbohydrate-based MOF, which was discovered serendipitously in 2010, was the first highly crystalline CD-MOF to be obtained. X-ray crystallography of a single crystal reveals that it adopts the space group I432 with unit cell dimensions of approximately 31 × 31 × 31 Å3. Other CD-MOFs, namely, CD-MOF-2 and CD-MOF-3, can be obtained when potassium ions are replaced by rubidium and cesium ions, respectively. CD-MOFs comprise extended body-centered frameworks of (γ-CD)6 cubic units, which contain spherical pores that reside at the center of the cubes, interconnected by alkali metal cations, forming both cylindrical and triangular channels.During the past decade, CD-MOFs have emerged as a useful class of multifunctional materials based on porous frameworks with extended structures displaying robust crystallinity, permanent porosity, and excellent biocompatibility. The family of CD-MOFs has been joined by a growing collection of metal nodes involving alkali metal cations (Li+, Na+, K+, Rb+, Cs+) and γ-CD as well as its derivatives. As a result of the ability of their extended porous frameworks to absorb guest molecules, including gases, drugs, metal-based nanoclusters, and nanoparticles, CD-MOFs have potential applications in areas as disparate as templating syntheses of metal-based nanoparticles and gels, adsorption and separation, trapping highly reactive intermediates, catalyst supports, sensing, electrical memory, and drug delivery.In this Account, we tell the story of CD-MOFs, a scientific discovery made in our research laboratory at Northwestern University, and the opportunities to use these environmentally friendly porous materials across different fields of science and technology. The story includes representative synthetic protocols for the preparation of CD-MOFs, along with an overview of their structural features, functionalization, and chemical modification aimed at increasing their stabilities in aqueous environments, and finally, a summary of their applications. The examples we will discuss, however, are only illustrative, and there is a significant body of additional findings emanating from our laboratory and others, especially in the realm of developing new synthetic strategies, tuning the framework stabilities, and exploring the guest inclusion and emergent properties of CD-MOFs. We refer readers to the original communications, papers, and reviews cited herein. We hope that, in the telling of the story of CD-MOFs, this Account may promote new scientific discoveries and further development of CD-MOF-based technologies in the future.

Modeling Oxidation of AlCoCrFeNi High-Entropy Alloy Using Stochastic Cellular Automata.

Together with the thermodynamics and kinetics, the complex microstructure of high-entropy alloys (HEAs) exerts a significant influence on the associated oxidation mechanisms in these concentrated solid solutions. To describe the surface oxidation in AlCoCrFeNi HEA, we employed a stochastic cellular automata model that replicates the mesoscale structures that form. The model benefits from diffusion coefficients of the principal elements through the native oxides predicted by using molecular simulations. Through our examination of the oxidation behavior as a function of the alloy composition, we corroborated that the oxide scale growth is a function of the complex chemistry and resultant microstructures. The effect of heat treatment on these alloys is also simulated by using reconstructed experimental micrographs. When they are in a single-crystal structure, no segregation is noted for α-Al2O3 and Cr2O3, which are the primary scale-forming oxides. However, a coexistent separation between Al2O3 and Cr2O3 oxide scales with the Al-Ni- and Cr-Fe-rich regions is predicted when phase-separated microstructures are incorporated into the model.

Photon Upconversion in a Glowing Metal-Organic Framework.

The interaction of low-energy light with matter that leads to the production of high-energy light is known as photon upconversion. This phenomenon is of importance because of its potential applications in optoelectronics, energy harvesting, and the biomedical arena. Herein, we report a pillared-paddlewheel metal-organic framework (MOF), constructed from a tetrakis(4-carboxyphenyl)porphyrin sensitizer and a dipyridyl thiazolothiazole annihilator, designed for efficient triplet-triplet annihilation upconversion (TTA-UC). Single-crystal X-ray diffraction studies reveal that the Zn-metalated sensitizers are coordinated to Zn2 nodes in a paddlewheel fashion, forming 2D sheets, to which are linked annihilators, such that each sensitizer is connected to five of them. The precise arrangements of sensitizers with respect to annihilators, and the high annihilator-to-sensitizer ratio, facilitate Dexter energy transfer. This level of organization in an extended structure leads to a high TTA-UC efficiency of 1.95% (theoretical maximum = 50%) at an excitation power density of 25 mW cm-2.

Host-Guest Complexation-Mediated Supramolecular Photon Upconversion.

The phenomenon of photon upconversion, in which a system absorbs two or more photons of lower energy and emits a photon of higher energy, has been used in numerous applications, including non-destructive bioimaging, deep-penetrating photodynamic therapy, catalysis, and photovoltaic devices. To date, photon upconversion has been observed typically in inorganic nanocrystals, nanoparticles, metal-organic frameworks, supramolecular assemblies, and organic dyads. Herein, we demonstrate a new strategy for harnessing photon upconversion-supramolecular upconversion-based on host-guest chemistry. We have identified a box-like fluorescent tetracationic host incorporating a thiazolothiazole emitter, which can accommodate a guest-sensitizer, 5,15-diphenylporphyrin, inside its cavity, and demonstrated that the host-guest inclusion complex displays triplet-fusion upconversion when the guest is excited with low-energy light. The strategy of supramolecular upconversion has been employed successfully in two other host-guest complexes-with hosts comprised of anthracene emitters and a 5,15-diphenylporphyrin guest-corroborating the fact that this strategy is a general one and can be applied to the design of a new family of host-guest complexes for photon upconversion. More importantly, supramolecular upconversion is accessible in solution under dilute conditions (µM) compared to most of the existing approaches that require significantly higher concentrations (mM) of emitters and/or sensitizers. Transient absorption spectroscopy and density functional theory have been employed in order to confirm a triplet-fusion upconversion mechanism. Host-guest complexation-mediated supramolecular photon upconversion eliminates multiple issues in the existing systems related to high working concentrations, high incident laser power, and low optical penetration depths.

Mechanical-Bond-Induced Exciplex Fluorescence in an Anthracene-Based Homo[2]catenane.

Collisional intermolecular interactions between excited states form short-lived dimers and complexes that lead to the emergence of excimer/exciplex emission of lower energy, a phenomenon which must be differentiated from the photoluminescence (PL) arising from the monomeric molecules. Although the utilization of noncovalent bonding interactions, leading to the generation of excimer/exciplex PL, has been investigated extensively, precise control of the aggregates and their persistence at very low concentrations remains a rare phenomenon. In the search for a fresh approach, we sought to obtain exciplex PL from permanent structures by incorporating anthracene moieties into pyridinium-containing mechanically interlocked molecules. Beyond the optical properties of the anthracene moieties, their π-extended nature enforces [π···π] stacking that can overcome the Coulombic repulsion between the pyridinium units, affording an efficient synthesis of an octacationic homo[2]catenane. Notably, upon increasing the ionic strength by adding tetrabutylammonium hexafluorophosphate, the catenane yield increases significantly as a result of the decrease in Coulombic repulsions between the pyridinium units. Although the ground-state photophysical properties of the free cyclophane and the catenane are similar and show a charge-transfer band at ∼455 nm, their PL characters are distinct, denoting different excited states. The cyclophane emits at ∼562 nm (quantum yield ϕF = 3.6%, emission lifetime τs = 3 ns in MeCN), which is characteristic of a disubstituted anthracene-pyridinium linker. By contrast, the catenane displays an exciplex PL at low concentration (10-8 M) with an emission band centered on 650 nm (ϕF = 0.5%, τs = 14 ns) in MeCN and at 675 nm in aqueous solution. Live-cell imaging performed in MIAPaCa-2 prostate cancer cells confirmed that the catenane exciplex emission can be detected at micromolar concentrations.

MultiCon: A Semi-Supervised Approach for Predicting Drug Function from Chemical Structure Analysis.

Semi-supervised learning has proved its efficacy in utilizing extensive unlabeled data to alleviate the use of a large amount of supervised data and improve model performance. Despite its tremendous potential, semi-supervised learning has yet to be implemented in the field of drug discovery. Empirical testing of drugs and their classification is costly and time-consuming. In contrast, predicting therapeutic applications of drugs from their structural formulas using semi-supervised learning would reduce costs and time significantly. Herein, we employ a new multicontrastive-based semi-supervised learning algorithm-MultiCon-for classifying drugs into 12 categories, according to therapeutic applications, on the basis of image analyses of their structural formulas. By rational use of data balancing, online augmentations of the drug image data during training, and the combined use of multicontrastive loss with consistency regularization, MultiCon achieves better class prediction accuracies when compared with the state-of-the-art machine learning methods across a variety of existing semi-supervised learning benchmarks. In particular, it performs exceptionally well with a limited number of labeled examples. For instance, with just 5000 labeled drugs in a PubChem (D3) data set, MultiCon achieved a class prediction accuracy of 97.74%.

Characteristics, outcome and risk factors for mortality of paediatric patients with ICU-acquired candidemia in India: A multicentre prospective study.

BACKGROUND: The epidemiology, clinical profile and outcome of paediatric candidemia vary considerably by age, healthcare settings and prevalent Candida species. Despite these differences, few comprehensive studies are undertaken. This nationwide study addresses this knowledge gap. METHODS: 487 children who contracted ICU-acquired candidemia at 23 Indian tertiary care centres were assessed for 398 variables spanning demography, clinical characteristics, microbiology, treatment and outcome. RESULTS: Both neonates (5.0 days; range = 3.0-9.5) and non-neonatal children (7.0 days; range = 3.0-13.0) developed candidemia early after ICU admission. Majority of neonates were premature (63.7%) with low birthweight (57.1%). Perinatal asphyxia (7.3%), pneumonia (8.2%), congenital heart disease (8.4%) and invasive procedures were common comorbidities, and antibiotic use (94.1%) was widespread. C tropicalis (24.7%) and C albicans (20.7%) dominated both age groups. Antifungal treatment (66.5%) and removal of central catheters (44.8%) lagged behind. Overall resistance was low; however, emergence of resistant C krusei and C auris needs attention. The 30-day crude mortality was 27.8% (neonates) and 29.4% (non-neonates). Logistic regression identified admission to public sector ICUs (OR = 5.64), mechanical ventilation (OR = 2.82), corticosteroid therapy (OR = 8.89) and antifungal therapy (OR = 0.22) as independent predictors of 30-day crude mortality in neonates. Similarly, admission to public sector ICUs (OR = 3.62), mechanical ventilation (OR = 3.13), exposure to carbapenems (OR = 2.18) and azole antifungal therapy (OR = 0.48) were independent predictors for non-neonates. CONCLUSIONS: Our findings reveal a distinct epidemiology, including early infection with a different spectrum of Candida species, calling for appropriate intervention strategies to reduce candidemia morbidity and mortality. Independent factors identified in our regression models can help tackle these challenges.

Supramolecular Tessellations by a Rigid Naphthalene Diimide Triangle.

Tessellation of organic polygons though [π···π] and charge-transfer (CT) interactions offers a unique opportunity to construct supramolecular organic electronic materials with 2D topologies. Our approach to exploring the 3D topology of 2D tessellations of a naphthalene diimide-based molecular triangle (NDI-Δ) reveals that the 2D molecular arrangement is sensitive to the identity of the solvent and solute concentrations. Utilization of nonhalogenated solvents, combined with careful tailoring of the concentrations, results in NDI-Δ self-assembling though [π···π] interactions into 2D honeycomb triangular and hexagonal tiling patterns. Cocrystallization of NDI-Δ with tetrathiafulvalene (TTF) leads systematically to the formation of 2D tessellations as a result of superstructure-directing CT interactions. Different solvents lead to different packing arrangements. Using MeCN, CHCl3, and CH2Cl2, we identified three sets of cocrystals, namely CT-A, CT-B, and CT-C, respectively. Solvent modulation plays a critical role in controlling not only the NDI-Δ:TTF stoichiometric ratios and the molecular arrangements in the crystal superstructures, but also prevents the inclusion of TTF guests inside the cavities of NDI-Δ. Confinement of TTF inside the NDI-Δ cavities in the CT-A superstructure enhances the CT character with the observation of a broad absorption band in the NIR region. In the CT-B superstructure, the CHCl3 lattice molecules establish a set of [Cl···Cl] and [Cl···S] intermolecular interactions, leading to the formation of a hexagonal grid of solvent in which NDI-Δ forms a triangular grid. In the CT-C superstructure, three TTF molecules self-assemble, forming a supramolecular isosceles triangle TTF-Δ, which tiles in a plane alongside the NDI-Δ, producing a 3 + 3 honeycomb tiling pattern of the two different polygons. Solid-state spectroscopic investigations on CT-C revealed the existence of an absorption band at 2500 nm, which on the basis of TDDFT calculations, was attributed to the mixed-valence character between two TTF•+ radical cations and one neutral TTF molecule.

A Supramolecular Approach for Modulated Photoprotection, Lysosomal Delivery, and Photodynamic Activity of a Photosensitizer.

Prompted by a knowledge of the photoprotective mechanism operating in photosystem supercomplexes and bacterial antenna complexes by pigment binding proteins, we have appealed to a boxlike synthetic receptor (ExBox·4Cl) that binds a photosensitizer, 5,15-diphenylporphyrin (DPP), to provide photoprotection by regulating light energy. The hydrophilic ExBox4+ renders DPP soluble in water and modulates the phototoxicity of DPP by trapping it in its cavity and releasing it when required. While trapping removes access to the DPP triplet state, a pH-dependent release of diprotonated DPP (DPPH22+) restores the triplet deactivation pathway, thereby activating its ability to generate reactive oxygen species. We have employed the ExBox4+-bound DPP complex (ExBox4+⊃DPP) for the safe delivery of DPP into the lysosomes of cancer cells, imaging the cells by utilizing the fluorescence of the released DPPH22+ and regulating photodynamic therapy to kill cancer cells with high efficiency.

Combining Intra- and Intermolecular Charge Transfer with Polycationic Cyclophanes To Design 2D Tessellations.

A series of donor-acceptor (D-A) naphthalene-viologen-based cyclophanes of different shapes, sizes, and symmetries have been synthesized and characterized. Solution optical studies on these cyclophanes reveal the existence of photoinduced intramolecular charge transfer (CT) at 465 nm from naphthalene (D) to viologen (A) units, resulting in a conformational change in the viologen units and the emergence of an emission at 540 nm. The D-A cyclophanes with box-like and hexagon-like shapes offer an opportunity to control the arrangement within 2D layers where D-A interactions direct the superstructures. While a box-like 2,6-disubstituted naphthalene-based tetracationic cyclophane does not form square tiling patterns, a truncated hexagon-like congener self-assembles to form a hexagonal superstructure which, in turn, adopts a hexagonal tiling pattern. Tessellation of the more rigid and highly symmetrical 2,7-disubstituted naphthalene-based cyclophanes leads to the formation of 2D square and honeycomb tiling patterns with the box-like and hexagon-like cyclophanes, respectively. Co-crystallization of the box-like cyclophanes with tetrathiafulvalene (TTF) results in the formation of D-A CT interactions between TTF and viologen units, leading to tubular superstructures. Co-crystallization of the hexagon-like cyclophane with TTF generates well-ordered and uniform tubular superstructures in which the TTF-viologen CT interactions and naphthalene-naphthalene [π···π] interactions propagate with 2D topology. In the solid state, the TTF-cyclophane co-crystals are paramagnetic and display dual intra- and intermolecular CT behavior at ∼470 and ∼1000 nm, respectively, offering multi-responsive materials with potential pathways for electron transport.

Melting of the Vortex Lattice through Intermediate Hexatic Fluid in an a-MoGe Thin Film.

The hexatic fluid refers to a phase in between a solid and a liquid that has short-range positional order but quasi-long-range orientational order. In the celebrated theory of Berezinskii, Kosterlitz, and Thouless and subsequently refined by Halperin, Nelson, and Young, it was predicted that a two-dimensional hexagonal solid can melt in two steps: first, through a transformation from a solid to a hexatic fluid, which retains quasi-long-range orientational order; and then from a hexatic fluid to an isotropic liquid. In this Letter, using a combination of real space imaging and transport measurements, we show that the two-dimensional vortex lattice in an a-MoGe thin film follows this sequence of melting as the magnetic field is increased. Identifying the signatures of various transitions on the bulk transport properties of the superconductor, we construct a vortex phase diagram for a two-dimensional superconductor.

Cyclotris(paraquat-p-phenylenes).

Reported here is the synthesis, solid-state characterization, and redox properties of new triangular, threefold symmetric, viologen-containing macrocycles. Cyclotris(paraquat-p-phenylene) (CTPQT6+ ) and cyclotris(paraquat-p-1,4-dimethoxyphenylene) (MCTPQT6+ ) were prepared and their X-ray single-crystal (super)structures reveal intricate three-dimensional packing. MCTPQT6+ results in nanometer-sized channels, in contrast with its parent counterpart CTPQT6+ which crystallizes as a couple of polymorphs in the form of intercalated assemblies. In the solid state, MCTPQT3(.+) exhibits stacks between the 1,4-dimethoxyphenylene and bipyridinium radical cations, providing new opportunities for the manipulation and control of the recognition motif associated with viologen radical cations. These redox-active cyclophanes demonstrate that geometry-matching and weak intermolecular interactions are of paramount importance in dictating the formation of their intricate solid-state superstructures.

ExTzBox: A Glowing Cyclophane for Live-Cell Imaging.

The ideal fluorescent probe for live-cell imaging is bright and non-cytotoxic and can be delivered easily into the living cells in an efficient manner. The design of synthetic fluorophores having all three of these properties, however, has proved to be challenging. Here, we introduce a simple, yet effective, strategy based on well-established chemistry for designing a new class of fluorescent probes for live-cell imaging. A box-like hybrid cyclophane, namely ExTzBox·4X (6·4X, X = PF6-, Cl-), has been synthesized by connecting an extended viologen (ExBIPY) and a dipyridyl thiazolothiazole (TzBIPY) unit in an end-to-end fashion with two p-xylylene linkers. Photophysical studies show that 6·4Cl has a quantum yield ΦF = 1.00. Furthermore, unlike its ExBIPY2+ and TzBIPY2+ building units, 6·4Cl is non-cytotoxic to RAW 264.7 macrophages, even with a loading concentration as high as 100 µM, presumably on account of its rigid box-like structure which prevents its intercalation into DNA and may inhibit other interactions with it. After gaining an understanding of the toxicity profile of 6·4Cl, we employed it in live-cell imaging. Confocal microscopy has demonstrated that 64+ is taken up by the RAW 264.7 macrophages, allowing the cells to glow brightly with blue laser excitation, without any hint of photobleaching or disruption of normal cell behavior under the imaging conditions. By contrast, the acyclic reference compound Me2TzBIPY·2Cl (4·2Cl) shows very little fluorescence inside the cells, which is quenched completely under the same imaging conditions. In vitro cell investigations underscore the significance of using highly fluorescent box-like rigid cyclophanes for live-cell imaging.