Local Validation of a National Orthopaedic Registry.

BACKGROUND/OBJECTIVE: Registries are limited by the quality of the data they collect. We aimed to measure the data entry error rate at a regional orthopaedic unit in a national arthroplasty registry and to assess a proposed intervention of restricting data entry to senior trainees. METHODS AND MATERIALS: A total of 200 primary and revision arthroplasty cases (119 hips, 81 knees) were randomly selected from a single year, 2020. The Irish National Orthopaedic Registry was examined for the grade of the trainee that populated the form and the accuracy of 24 parameters by comparison with data recorded elsewhere in the patient record. RESULTS: The mean number of errors per form was 2.17 (95% confidence interval (CI): 1.95-2.39), giving an overall error rate of 9% (95% CI: 8%-10.0%). Eighty-seven percent of forms examined contained inaccuracies, ranging from one to nine errors (4%-38%). Some parameters were more prone to errors, ranging from 1% to 28%. There was no evidence of total errors varying by trainee grade (analysis of variance (ANOVA) p-value: 0.34). CONCLUSIONS: Error rates were in line with the literature. Results did not support restricting data entry to senior trainees.

Free base porphyrin-cyanine dye conjugate: synthesis and optical properties.

The covalent combination of a cyanine dye (IR-783) with a tetraphenyl porphyrin unit through an ether linkage results in a photoactive system capable of producing singlet oxygen. The synthesis, characterization and photophysical properties of the resulting novel free base porphyrin-cyanine conjugate named TPPO-IR-783 (TOI) is reported. Excited state properties were studied in various solvents with differing polarity. The fluorescence is strongly solvent dependent, however this is not the case for singlet oxygen phosphorescence, which is only observed in tetrahydrofuran (THF), when comparing 8 different polar, non-polar and medium-polarity solvents. This novel type of porphyrin-cyanine photosensitizer has the ability to produce singlet oxygen and absorbs light at NIR wavelengths.

Spin Orbit Coupling in Orthogonal Charge Transfer States: (TD-)DFT of Pyrene-Dimethylaniline.

The conformational dependence of the matrix element for spin-orbit coupling and of the electronic coupling for charge separation are determined for an electron donor-acceptor system containing a pyrene acceptor and a dimethylaniline donor. Different kinetic and energetic aspects that play a role in the spin-orbit charge transfer intersystem crossing (SOCT-ISC) mechanism are discussed. This includes parameters related to initial charge separation and the charge recombination pathways using the Classical Marcus Theory of electron transfer. The spin-orbit coupling, which plays a significant role in charge recombination to the triplet state, can be probed by (TD)-DFT, using the latter as a tool to understand and predict the SOCT-ISC mechanism. The matrix elements for spin-orbit coupling for acetone and 4-thio-thymine are used for benchmarking. (Time Dependent-) Density Functional Theory (DFT and TD-DFT) calculations are applied using the quantum chemical program Amsterdam Density Functional (ADF).

Structural effects of meso-halogenation on porphyrins.

The use of halogens in the crystal engineering of supramolecular porphyrin assemblies has been a topic of strong interest over the past decades. With this in mind we have characterized a series of direct meso-halogenated porphyrins using single crystal X-ray crystallography. This is accompanied by a detailed conformational analysis of all deposited meso-halogenated porphyrins in the CSD. In this study we have used the Hirshfeld fingerprint plots together with normal-coordinate structural decomposition and determined crystal structures to elucidate the conformation, present intermolecular interactions, and compare respective contacts within the crystalline architectures. Additionally, we have used density functional theory calculations to determine the structure of several halogenated porphyrins. This contrasts conformational analysis with existing X-ray structures and gives a method to characterize samples that are difficult to crystallize. By using the methods outlined above we were able to deduce the impact a meso halogen has on a porphyrin, for example, meso-halogenation is dependent on the type of alternate substituents present when forming supramolecular assemblies. Furthermore, we have designed a method to predict the conformation of halogenated porphyrins, without need of crystallization, using DFT calculations with a high degree of accuracy.

Development of Phenalenone-Triazolium Salt Derivatives for aPDT: Synthesis and Antibacterial Screening.

The increasing number of hospital-acquired infections demand the development of innovative antimicrobial treatments. Antimicrobial photodynamic therapy (aPDT) is a versatile technique which relies on the production of reactive oxygen species (ROS) generated by light-irradiated photosensitizers (PS) in the presence of oxygen (O2). 1H-Phenalen-1-one is a very efficient photosensitizer known for its high singlet oxygen quantum yield and its antimicrobial potential in aPDT when covalently bound to quaternary ammonium groups. Triazolium salts are stable aromatic quaternary ammonium salts that recently appeared as interesting moieties endowed with antimicrobial activities. The coupling between phenalenone and triazolium groups bearing various substituents was realized by copper-catalyzed azide-alkyne cycloaddition followed by alkylation with methyl iodide or 2-(bromomethyl)-1H-phenalen-1-one. As expected, most of the compounds retained the initial singlet oxygen quantum yield, close to unity. Minimum inhibitory concentrations (MIC) of 14 new phenalenone-triazolium salt derivatives and 2 phenalenone-triazole derivatives were determined against 6 bacterial strains (Gram-negatives and Gram-positives species). Most of these PS showed significant photoinactivation activities, the strongest effects being observed against Gram-positive strains with as low as submicromolar MIC values.

Giant Left Ventricular Papillary Fibroelastoma Presented as Transient Ischemic Attack and Complicated by Post-Pericardiotomy Syndrome.

Papillary fibroelastoma is a benign cardiac tumour that most commonly presents as an incidental finding on imaging but may present with an acute neurological event due to embolic phenomena. We report a 51-year-old female who presented with focal neurology of the right hand that lasted for 30 minutes. Her initial investigations including CT-brain were unremarkable, and given her low-risk profile for stroke she was discharged for routine outpatient workup of possible transient ischaemic attack. Transthoracic echo detected a large mobile mass attached to the left ventricular wall. This was mistakenly diagnosed as a left ventricular thrombus, for which she was commenced on warfarin. After three months on warfarin without reduction in the size of the mass, cardiac MRI was performed. The scan was repeated as the initial imaging failed to demonstrate the tumour. This was followed by positron emission tomography which suggested a benign mass of the left ventricle. The patient underwent surgical excision of the tumour and developed post-pericardiotomy syndrome. Histopathology confirmed papillary fibroelastoma. Though rare, cardiac neoplasm may remain a differential diagnosis for acute neurological presentations in non-classical patients.

Elucidating Atropisomerism in Nonplanar Porphyrins with Tunable Supramolecular Complexes.

Atropisomerism is a fundamental feature of substituted biaryls resulting from rotation around the biaryl axis. Different stereoisomers are formed due to restricted rotation about the single bond, a situation often found in substituted porphyrins. Previously NMR determination of porphyrin atropisomers proved difficult, if not almost impossible to accomplish, due to low resolution or unresolvable resonance signals that predominantly overlapped. Here, we shed some light on this fundamental issue found in porphyrinoid stereochemistry. Using benzenesulfonic acid (BSA) for host-guest interactions and performing 1D, 2D NMR spectroscopic analyses, we were able to characterize all four rotamers of the nonplanar 5,10,15,20-tetrakis(2-aminophenyl)-2,3,7,8,12,13,17,18-octaethylporphyirin as restricted H-bonding complexes. Additionally, X-ray structural analysis was used to investigate aspects of the weak host-guest interactions. A detailed assignment of the chemical signals suggests charge-assisted complexation as a key to unravel the atropisomeric enigma. From a method development perspective, symmetry operations unique to porphyrin atropisomers offer an essential handle to accurately identify the rotamers using NMR techniques only.

Making triplets from photo-generated charges: observations, mechanisms and theory.

Triplet formation by charge recombination is a phenomenon that is encountered in many fields of the photo-sciences and can be a detrimental unwanted side effect, but can also be exploited as a useful triplet generation method, for instance in photodynamic therapy. In this Perspective we describe the various aspects that play a role in the decay of charge separated states into local triplet states. The observations and structures of a selection of (pre-2015) molecular electron donor-acceptor systems in which triplet formation by charge recombination occurs are reported. An overview is given of some more recent systems consisting of BODIPY dimers, and BODIPYs attached to various electron-donor units displaying this same triplet formation process. A selection of polymer-fullerene blends in which triplet formation by (non-geminate) charge recombination has been observed, is presented. Furthermore, in-depth information regarding the mechanistic aspects of triplet formation by charge recombination is given on spin dephasing, through hyperfine interactions, as well as on spin-orbit coupling occurring simultaneously with charge recombination. The limits and constraints of these factors and their role in intersystem crossing are discussed. A pictorial view of the two mechanisms is given and this is correlated to aspects of the selection rules for triplet formation, the so-called El-Sayed rules. It is shown that the timescale of triplet formation by charge recombination is indicative for the mechanism that is responsible for the process. The relatively slow rates (CRkT ∼ 1 × 108 s-1 or slower) can be correlated to proton hyperfine interactions (also called the radical pair mechanism), but substantially faster rates (CRkT ∼ 1 × 109 up to 2.5 × 1010 s-1 or faster) have to be correlated to spin-orbit coupling effects. Several examples of molecular systems showing such fast rates are available and their electron donor and acceptor orbitals display an orthogonal relationship with respect to each other. This orientation of (the nodal planes of) the π-orbitals of the donor and acceptor units is correlated to the mechanisms in photodynamic agents and photovoltaic blends.

Conformational Re-engineering of Porphyrins as Receptors with Switchable N-H⋠⋠⋠X-Type Binding Modes.

The selectivity and functional variability of porphyrin cofactors are typically based on substrate binding of metalloporphyrins wherein the pyrrole nitrogen units only serve to chelate the metal ions. Yet, using the porphyrin inner core system for other functions is possible through conformational engineering. As a first step towards porphyrin "enzyme-like" active centers, a structural and spectroscopic study of substrate binding to the inner core porphyrin system shows that a highly saddle-distorted porphyrin with peripheral amino receptor groups (1, 2,3,7,8,12,13,17,18-octaethyl-5,10,15,20-tetrakis(2-aminophenyl)porphyrin) coordinates analytes in a switchable manner dependent on the acidity of the solution. The supramolecular ensemble exhibits exceptionally high affinity to and selectivity for the pyrophosphate anion (2.26±0.021)×109 m-1 . 1 H NMR spectroscopic studies provided insight into the likely mode of binding and the characterization of atropisomers, all four of which were also studied by X-ray crystallography.

Structure and conformation of photosynthetic pigments and related compounds. 15. Conformational analysis of chlorophyll derivatives - implications for hydroporphyrins in vivo.

Chlorophylls are fundamental macrocyclic cofactors in photosynthetic reaction centers and light-harvesting complexes. Their biological function is well understood on the basis of protein structural data and a significant body of information indicates that the conformation of tetrapyrroles plays a large role in controlling their biological activity. While there is no small molecule crystal structure of chlorophyll, the normal-coordinate structural decomposition (NSD) method is a very useful analytical tool for conformational analysis of chlorophylls, using tetrapyrroles that mimic their structure. NSD allows for an analysis of the individual macrocyclic distortion modes and their contributions to the overall conformation. Herein, we present our own validation of the NSD program and use it to carry out a conformational analysis of chlorophyll-related compounds. Metal insertions, peripheral substituents, and solvents in the unit cell give rise to different NSD profiles in chlorophyll derivatives. These range from planar and non-planar conformations upon metal insertions, to polar peripheral substituents, and fused rings in chlorins. Substituent effects are clearly evidenced in highly ß-substituted chlorins and while bacteriochlorins and isobacteriochlorins experience similar effects to the chlorins, they are also subject to solvent effects, causing the macrocycle to be non-planar. Overall, we report a first conformational analysis of all 'chlorophyll'-related small molecule crystal structures at an atomic level.

Functionalization of Deutero- and Protoporphyrin IX Dimethyl Esters via Palladium-Catalyzed Coupling Reactions.

Herein, we report the functionalization of the ß-positions of deutero- and protoporphyrin IX dimethyl esters. Initial halogenations were carried out on both deutero- and protoporphyrin IX dimethyl esters. Although previously reported, vastly optimized yields with respect to deuteroporphyrin halogenation were obtained. Methods were developed for the bromination of the vinyl groups of protoporphyin IX dimethyl ester. Subsequent palladium-catalyzed coupling reactions were utilized to modify the periphery of these naturally occurring porphyrin derivatives with a variety of functionalities. The described Suzuki, Sonogashira, and "Click" reactions demonstrate the ease at which these porphyrins may be manipulated and even interchangeable, as will be discussed for one example. X-ray crystallographic analysis successfully determined the structure of two derivatives synthesized. Results identified a unique head-to-tail stacking pattern for 3,8-diphenyldeuteroporphyrin IX dimethyl ester, most likely due to the presence of additional aromatic moieties on the periphery of the porphyrin.

Crystal structure and synthesis of 3-(1H-pyrrol-2-yl)-1-(thio-phen-2-yl)propanone.

The title compound, C11H9NOS, was obtained in an improved yield compared to previous literature methods. The mol-ecule is essentially planar with a maximum deviation of 0.085 Šfrom the mean plane through all non-H atoms. There is directive inter-molecular hydrogen bonding in the form of N-H⋯O hydrogen bonds with a distance of 2.889 (3) Šbetween the pyrrole amine and the ketone carbonyl O atom. The resulting hydrogen-bonding network defines a ribbon parallel to the a axis. These ribbons form offset stacks along the b axis.