Delocalized quinolinium-macrocyclic peptides, an atypical chemotype for CNS penetration.

Macrocyclic drugs can address an increasing range of molecular targets but enabling central nervous system (CNS) access to these drugs has been viewed as an intractable problem. We designed and synthesized a series of quinolinium-modified cyclosporine derivatives targeted to the mitochondrial cyclophilin D protein. Modification of the cation to enable greater delocalization was confirmed by x-ray crystallography of the cations.

Cervical Cancer Screening Positivity Among Women Living With HIV in CDC-PEPFAR Programs 2018-2022.

Background: The US President's Emergency Plan for AIDS Relief aims to address the higher risk of cervical cancer among women living with HIV by offering high-quality screening services in the highest burden regions of the world.

Methods: We analyzed the US President's Emergency Plan for AIDS Relief Monitoring, Evaluation, and Reporting data from Centers for Disease Control and Prevention-supported sites in 13 countries in sub-Saharan Africa for women living with HIV aged older than 15 years who accessed cervical cancer screening services (mostly visual inspection, with ablative or excisional treatment offered for precancerous lesions), April 2018-March 2022. We calculated the positivity by age, country, and clinical visit type (first lifetime screen or routine rescreening).

An [Fe] molecular oxyhydroxide.

An [Fe] hexagonal bipyramid displays antiferromagnetic exchange between the two capping tetrahedral ions and the six ring octahedral ions resulting in a spin ground state of = 10.

Stable Platinum(IV) Corroles: Synthesis, Molecular Structure, and Room-Temperature Near-IR Phosphorescence.

A series of stable Pt(IV) corrole complexes with the general formula Pt[TXPC](/-CHCN)(py), where TXPC is the trianion of a tris(-X-phenyl)corrole and X = CF, H, and CH, has been synthesized, affording key physicochemical data on a rare and elusive class of metallocorroles. Single-crystal X-ray structures of two of the complexes revealed very short equatorial Pt-N distances of 1.94-1.

Rapid one-pot synthesis of pyrrole-appended isocorroles.

Free-base meso-triarylcorroles have been found to undergo oxidative coupling with an excess of pyrrole in dichloromethane in the presence of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) affording 5/10-pyrrole-appended isocorroles in reasonable yields (35-60%) and in a matter of seconds. The free-base isocorrole ligands could all be complexed to copper with Cu(OAc)2·H2O in chloroform/methanol in 55-80% yields. Single-crystal X-ray structures of two of the new compounds (H2[5-pyr-TpOMePiC] and Cu[10-pyr-TpOMePiC]) revealed planar macrocycles with rms atomic displacements of only 0.

Relativistic Effects on a Metal-Metal Bond: Osmium Corrole Dimers.

A series of metal-metal bonded osmium corrole dimers, {Os[T pXPC]}, were synthesized in reasonably good yields (35-46%) via the interaction of the corresponding free-base meso-tris( p-X-phenyl)corroles (H[T pXPC], X = CF, H, CH, and OCH), Os(CO), and potassium carbonate in 1,2,4-trichlorobenzene under an inert atmosphere at 180 °C over several hours. The complexes are only the second class of Os corroles reported to date (the first being OsN corroles) and also the second class of metal-metal bonded metallocorrole dimers (the other being Ru corrole dimers). Comparison of the X-ray structures, redox potentials, and optical spectra of analogous Ru and Os corrole dimers, along with scalar-relativistic DFT calculations, has provided an experimentally calibrated account of relativistic effects in these complexes.

A Three-Dimensional Dynamic Supramolecular "Sticky Fingers" Organic Framework.

Engineering high-recognition host-guest materials is a burgeoning area in basic and applied research. The challenge of exploring novel porous materials with advanced functionalities prompted us to develop dynamic crystalline structures promoted by soft interactions. The first example of a pure molecular dynamic crystalline framework is demonstrated, which is held together by means of weak "sticky fingers" van der Waals interactions.

Hydrolytic stability in hemilabile metal-organic frameworks.

Highly porous metal-organic frameworks (MOFs), which have undergone exciting developments over the past few decades, show promise for a wide range of applications. However, many studies indicate that they suffer from significant stability issues, especially with respect to their interactions with water, which severely limits their practical potential. Here we demonstrate how the presence of 'sacrificial' bonds in the coordination environment of its metal centres (referred to as hemilability) endows a dehydrated copper-based MOF with good hydrolytic stability.

Electronic Structure of Manganese Corroles Revisited: X-ray Structures, Optical and X-ray Absorption Spectroscopies, and Electrochemistry as Probes of Ligand Noninnocence.

Presented herein is a detailed multitechnique investigation of ligand noninnocence in S = / manganese corrole derivatives at the formal Mn oxidation state. The Soret maxima of Mn[T pXPC]Cl (T pXPC = meso-tris( p-X-phenyl)corrole, where X = CF, H, Me, and OMe) were found to red-shift over a range of 37 nm with increasing electron-donating character of X. For Mn[T pXPC]Ph, in contrast, the complex Soret envelopes were found to be largely independent of X.

A robust and unique iron(ii) mosaic-like MOF.

A novel extended triazole-based ligand (PM-Tria) has been synthesized and an unprecedented MOF 3D has serendipitously been formed by assembling iron(ii), PM-Tria ligand and fluoride anions. This MOF contains a perfectly linear one-dimensional {Fe(ii)-F}n bridging chain that shows an antiferromagnetic behaviour. Furthermore, the structure is compared with a 14th century mosaic found in the Alhambra Palace in Granada showing a surprising symmetry resemblance.

Synthesis and Molecular Structure of a Copper Octaiodocorrole.

Although rather delicate on account of their propensity to undergo deiodination, β-octaiodoporphyrinoids are of considerable interest as potential precursors to novel β-octasubstituted macrocycles. Presented herein are early results of our efforts to synthesize β-octaiodocorrole derivatives. Oxidative condensation of 3,4-diiodopyrrole and aromatic aldehydes failed to yield free-base octaiodocorroles.

Enhancement of CO Uptake and Selectivity in a Metal-Organic Framework by the Incorporation of Thiophene Functionality.

The complex [Zn(tdc)dabco] (Htdc = thiophene-2,5-dicarboxylic acid; dabco = 1,4-diazabicyclooctane) shows a remarkable increase in carbon dioxide (CO) uptake and CO/dinitrogen (N) selectivity compared to the nonthiophene analogue [Zn(bdc)dabco] (Hbdc = benzene-1,4-dicarboxylic acid; terephthalic acid). CO adsorption at 1 bar for [Zn(tdc)dabco] is 67.4 cm·g (13.

Halterman Corroles and Their Use as a Probe of the Conformational Dynamics of the Inherently Chiral Copper Corrole Chromophore.

Halterman corroles have been synthesized for the first time from pyrrole and Halterman's aldehyde via Gryko's "water-methanol method". These were derivatized to the corresponding copper complexes and subsequently to the β-octabromo complexes. Electronic circular dichroism spectra were recorded for the enantiopure copper complexes, affording the first such measurements for the inherently chiral Cu corrole chromophore.

Electronic Structure of Cobalt-Corrole-Pyridine Complexes: Noninnocent Five-Coordinate Co(II) Corrole-Radical States.

Two sets of complexes of Co-triarylcorrole-bispyridine complexes, Co[TpXPC](py) and Co[BrTpXPC](py) have been synthesized, where TpXPC refers to a meso-tris(para-X-phenyl)corrole ligand with X = CF, H, Me, and OMe and BrTpXPC to the corresponding β-octabrominated ligand. The axial pyridines in these complexes were found to be labile and, in dilute solutions in dichloromethane, the complexes dissociate almost completely to the five-coordinate monopyridine complexes. Upon addition of a small quantity of pyridine, the complexes revert back to the six-coordinate forms.

Cobalt- and Rhodium-Corrole-Triphenylphosphine Complexes Revisited: The Question of a Noninnocent Corrole.

A reinvestigation of cobalt-corrole-triphenylphosphine complexes has yielded an unexpectedly subtle picture of their electronic structures. UV-vis absorption spectroscopy, skeletal bond length alternations observed in X-ray structures, and broken-symmetry DFT (B3LYP) calculations suggest partial Co-corrole character for these complexes. The same probes applied to the analogous rhodium corroles evince no evidence of a noninnocent corrole.

The remarkable influence of N,O-ligands in the assembly of a bis-calix[4]arene-supported [MnMnMn] cluster.

Calix[4]arenes are versatile ligands, capable of supporting the formation of a wide variety of polymetallic clusters comprising 3d, 4f or 3d-4f metal ions. Calixarene-based metal ion fragments act as both bridging and structure capping moieties in these systems, and this behaviour is systematically extended upon moving to bis-calix[4]arene, a relatively new ligand in which two calix[4]arenes are tethered at the methylene bridge position. N,O-Ligands greatly influence cluster formation with bis-calix[4]arene, affording a remarkable mixed-valence [MnMnMn] cluster that displays coordination chemistry typical of each ligand type, but also new structure capping behaviour for the latter.

Chiral transcription in self-assembled tetrahedral EuL chiral cages displaying sizable circularly polarized luminescence.

Predictable stereoselective formation of supramolecular assembly is generally believed to be an important but complicated process. Here, we show that point chirality of a ligand decisively influences its supramolecular assembly behavior. We designed three closely related chiral ligands with different point chiralities, and observe their self-assembly into europium (Eu) tetrametallic tetrahedral cages.

Structural Diversities in Heterometallic Mn-Ca Cluster Chemistry from the Use of Salicylhydroxamic Acid: {MnCa}, {MnCa}, {MnCa}, and {MnCa} Complexes with Relevance to Both High- and Low-Valent States of the Oxygen-Evolving Complex.

One-pot reactions between the [MnO(OCPh)(py)] triangular precursors and either CaBr·xHO or CaCl·6HO, in the presence of salicylhydroxamic acid (shaH), have afforded the heterometallic complexes [MnCa(OCPh)(shi)(HO)(MeCO)] (1) and (pyH)[MnMnCaCl(OCPh)(shi)(py)] (2), respectively, in good yields. Further reactions but using a more flexible synthetic scheme comprising the Mn(NO)·4HO/Ca(NO)·4HO and Mn(OCPh)·2HO/Ca(ClO)·4HO "metal blends" and shaH, in the presence of external base NEt, led to the new complexes (NHEt)[MnMnCa(OEt)(shi)(EtOH)] (3) and (NHEt)[MnCa(CO)(shi)] (4), respectively. In all reported compounds, the anion of the tetradentate (N,O,O,O)-chelating/bridging ligand salicylhydroxime (shi), resulting from the in situ metal-ion-assisted amide-iminol tautomerism of shaH, was found to bridge both Mn and Ca atoms.

Relativistic effects in metallocorroles: comparison of molybdenum and tungsten biscorroles.

The homoleptic sandwich compounds - Mo and W biscorroles - have afforded a novel platform for experimental studies of relativistic effects. A 200 mV difference in reduction potential and a remarkable 130 nm shift of a near-IR spectral feature have been identified as manifestations of relativistic effects on the properties of these complexes.

Stabilization and Structure of the cis Tautomer of a Free-Base Porphyrin.

Single-crystal X-ray analysis of the β-heptakis(trifluoromethyl)-meso-tetrakis(p-fluorophenyl)porphyrin, H [(CF ) TpFPP], has revealed the first example of a stable cis tautomer of a free-base porphyrin, the long-postulated intermediate of porphyrin tautomerism. The stability of the unique molecule appears to reflect a dual origin: a strongly saddled porphyrin skeleton, which alleviates electrostatic repulsion between the two NH protons, and two polarization-enhanced, transannular N-H⋅⋅⋅O-H⋅⋅⋅N hydrogen bond chains, each involving a molecule of water. DFT calculations suggest that the observed tautomer has a lower energy than the alternative, doubly hydrated trans tautomer by some 8.

Crystal structure resolution of two different chlorhexidine salts.

Two salts of the chlorhexidine di-cation (HCHx) - (HCHx)(SO)·3HO and (HCHx)(CO)·4HO - have been synthesised and characterised crystallographically.

Coordination polymers of 5-substituted isophthalic acid.

The synthesis and characterisation of five coordination polymers - Ni(mip)(HO)·2HO (), Zn(mip)(OH)(HO)·7.4HO (), Zn(mip)(OH)(HO)·4HO (), Mn(HMeOip) (), and Mn(tbip)(Htbip)(EtOH) () - are reported. Preliminary nitric oxide release data on compounds and are also given.

An indirect generation of 1D M(II)-2,5-dihydroxybenzoquinone coordination polymers, their structural rearrangements and generation of materials with a high affinity for H2, CO2 and CH4.

A series of solid-state structural transformations are found to accompany desolvation of relatively simple coordination polymers to yield materials that exhibit unexpected gas sorbing properties. Reaction of 1,2,4,5-tetrahydroxybenzene with M(II) salts (M = Mg, or Zn) in an alcohol/water solution in the presence of air affords cis-M(II)(C6H2O4(-II))(H2O)2·2H2O·xROH, (M = Mg, or Zn), crankshaft-like chains in which the absolute configurations of the chiral metal centres follow the pattern Δ Δ Λ Λ Δ Δ Λ Λ, and are hydrogen bonded together to generate spacious channels. When crystals of the crankshaft chain are air dried the crystals undergo a single crystal-to-powder rearrangement to form linear trans-M(II)(C6H2O4(-II))(H2O)2 chains.

Coordination polymers of Zn(II) and 5-methoxy isophthalate.

Solvothermal reaction of Zn(OAc)2 and 5-methoxy isophthalic acid (H2MeOip) in aqueous alcohols ROH (R = H, Me, Et, or (i)Pr) affords four different novel coordination polymers. Zn2(HMeOip)(MeOip)(OAc) (1) forms as a 1D 'ribbon of rings' polymer. Zn6(MeOip)4.

Liquid-phase enantioselective chromatographic resolution using interpenetrated, homochiral framework materials.

Effective separation of mixtures of enantiomers is of continuing interest in analytical and preparative chromatography, with new materials frequently designed and tested. We report two new enantiomerically pure 2D→3D interpenetrated materials used as stationary liquid chromatographic (LC) phases that are shown to resolve selected racemic mixtures with enantiomeric and chemical selectivity. Dicarboxylate ligands derived from amino acids on naphthalene and perylene cores form 2D frameworks that interpenetrate to give 3D structures.