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The identification of effective and druggable cholinesterase inhibitors to treat progressive neurodegenerative Alzheimer's disorder remains a continuous drug discovery hunt. In this perspective, the present study investigates the design and discovery of pyrimidine-morpholine hybrids (5a-l) as potent cholinesterase inhibitors. Palladium-catalyzed Suzuki-Miyaura cross-coupling reaction was employed to introduce the structural diversity on the pyrimidine heterocyclic core. A range of commercially available boronic acids was successfully coupled showing a high functional group tolerance. In vitro cholinesterase inhibitory potential using Ellman's method revealed significantly strong potency. Compound 5h bearing a meta-tolyl substituent at 2-position of pyrimidine ring emerged as a lead candidate against AChE with an inhibitory potency of 0.43 ± 0.42 µM, ∼38-fold stronger value than neostigmine (IC 50  = 16.3 ± 1.12 µM). Compound 5h also showed the lead inhibition against BuChE with an IC 50 value of 2.5 ± 0.04 µM. The kinetics analysis of 5h revealed the non-competitive mode of inhibition against AChE whereas computational modelling results of potent leads depicted diverse contacts with the binding site amino acid residues. Molecular dynamics simulations revealed the stability of biomolecular system, while, ADME analysis demonstrated druglikeness behaviour of potent compounds. Overall, the investigated pyrimidine-morpholine scaffold presented a remarkable potential to be developed as efficacious anti-Alzheimer's drugs., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Inc. All rights reserved.)

The vibrational and electronic properties of six systematically altered donor-acceptor dyes were investigated with density functional theory (DFT), spectroscopy, and electrochemical techniques. The dyes incorporated a carbazole donor connected to a dithieno[3,2-b:2',3'-d]thiophene linker at either the C 2 ( m ) or C 3 ( p ) position. Indane-based acceptors contained either dimalononitrile ( IndCN ), ketone and malononitrile ( InOCN ) or diketone ( IndO ) electron accepting groups. Molecular geometries modeled by DFT using the BLYP functional and def2-TZVP basis set showed planar geometries containing large, extended π-systems and produced Raman spectra consistent with the experimental data. Electronic absorption spectra had transitions with π-π* character at wavelengths below 325 nm and a charge transfer (CT) transition region from 500 to 700 nm. The peak wavelength was dependent on the donor and acceptor architecture, with each modulating the HOMO and LUMO levels, respectively, supported by TD-DFT estimates using the LC-ωPBE* functional and 6-31g(d) basis set. The compounds showed emission in solution with quantum yields ranging from 0.004 to 0.6 and lifetimes of less than 2 ns. These were assigned to either π-π* or CT emissive states. Signals attributed to CT states exhibited positive solvatochromism and thermochromism. The spectral emission behavior of each compound trended with the acceptor unit moieties, where malononitrile units lead to greater π-π* character and ketones exhibited greater CT character.

The racemic title compound, C 34 H 32 OS 2 , comprises an atropisomeric binaphthyl di-thio-acetal substituted at the methyl-ene carbon atom with a chiral benzyl alcohol. The two naphthalene ring systems are additionally substituted at the 3,3'-position with isopropyl groups. The overall stereochemistry is defined as aS,R and aR,S . The hydroxyl group forms an intra-molecular O-H⋯S hydrogen bond to one of the sulfur atoms. The crystal structure contains weak C-H⋯π inter-actions that link the mol-ecules into extended arrays., (© Beare et al. 2023.)

The closely related title compounds, 1-(di-naphtho-[2,1- d :1',2'- f ][1,3]dithiepin-4-yl)-2,2-di-methyl-propan-1-ol, C 26 H 24 OS 2 , 1 and 2-(di-naphtho-[2,1- d :1',2'- f ][1,3]dithiepin-4-yl)-3,3-di-methyl-butan-2-ol, C 27 H 26 OS 2 , 2 , both comprise an atrop-isomeric binaphthyl di-thio-acetal unit substituted at the methyl-ene carbon atom with a chiral neopentyl alcohol grouping. The overall stereochemistry of the racemate in each case is defined as aS,R and aR,S . In 1 , the hydroxyl group generates inversion dimers via pairwise inter-molecular O-H⋯S hydrogen bonds whereas in 2 , the O-H⋯S link is intra-molecular. Weak C-H⋯π inter-actions link the mol-ecules into extended arrays in both structures., (© Beare et al. 2023.)

Flavonoids acylated on their core phenolic groups are rare. The Aotearoa New Zealand endemic alpine daisy Celmisia viscosa is widespread, but its flavonoids have not previously been identified. Leaf extracts yielded a series of 8- O -acylated flavones with combinations of 3-methylbutanoate, 2-methylbutanoate, and 2-methylpropanoate groups and one, two, or three O -methyls, all previously unreported. Regiochemistries of 8-(3″-methylbutanoyl)-5-hydroxy-6,7,4'-trimethoxyflavone ( 5 ) and 8-(2″-methylbutanoyl)-5,7,4'-trihydroxy-6-methoxyflavone ( 10 ) were defined by X-ray crystallography. LC analyses of leaf extracts from the full geographic range of C. viscosa showed intraspecific variation of these flavones: most had high concentrations of trimethoxy 8- O -acylated flavones, but dimethoxy 8- O -acylated flavones were the most abundant flavonoids in two individuals. Three other viscid (sticky leaved) Celmisa species also contained these rare flavones, but four nonviscid Celmisa had none detectable.

A strategy for the generation of heterotrimetallic double cavity (DC) cages [Pd n Pt m L 4 ] 6+ (DC1: n=1, m=2; and DC2: n=2, m=1) is reported. The DC cages were generated by combining an inert platinum(II) tetrapyridylaldehyde complex with a suitably substituted pyridylamine and Pd II ions. 1 H and DOSY nuclear magnetic resonance spectroscopy (NMR) and electrospray ionization mass spectrometry (ESIMS) data were consistent with the formation of the DC architectures. DC1 and DC2 were shown to interact with several different guest molecules. The structure of DC1, which features two identical cavities, binding two 2,6-diaminoanthraquinone (DAQ) guest molecules was determined by single-crystal X-ray crystallography. In addition, DC1 was shown to bind two molecules of 5-fluorouracil (5-FU) in a statistical (non-cooperative) manner. In contrast, DC2, which features two different cage cavities, was found to interact with two different guests, 5-FU and cisplatin, selectively., (© 2022 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

Background: Intraoperative hemorrhage is a major cause of poor post-operative outcome. Beta-chitin patch has previously been found to be an effective haemostat, but whether modifying the patch can improve its efficacy and safety, remains unknown. In this study, beta-chitin patches were modified using polyethylene oxide, Pluronic-F127 (Chi/F127), calcium (Chi/20%Ca), increased thickness (Chi/Thick) or polyphosphate (Chi/PP)., Objective: Using rat (Wistar Albino; 8-10 weeks old) vascular and neurosurgical models, this project investigated and compared the efficacy and safety of beta-chitin patches with gauze, Surgicel and FloSeal., Methods: Ninety rats underwent a standardized femoral artery injury and were randomized to receive either beta-chitin patches, gauze, Surgicel or FloSeal. The bleeding time and total blood loss was measured. For the neurosurgical model, forty-four rats underwent a standardized cortical injury and randomization to a treatment group. Following a 48 h recovery period, their brains were collected for histopathological examination., Results: The mean bleeding time with Chitin (120.8 s) and Chi/PP (117.3 s) was ~60 s lower than Chi/F127, Chi/20%Ca and Chi/Thick ( p < 0.05). Chitin and Chi/PP had a significantly lower bleeding time than FloSeal (174.2 s) ( p < 0.05), but not Surgicel (172.7 s). Gauze (400 s) had a significantly higher bleeding time compared to all other groups ( p < 0.05). There were no significant differences in the total blood loss between the groups. Histopathological examination of brains found no adverse inflammatory reaction to any of the haemostatic compounds., Conclusion: Chi/PP had superior haemostatic efficacy compared to Surgicel and FloSeal, but not compared to non-modified beta-chitin patch. All of the haemostats were equally safe., Competing Interests: AJ and P-JW are inventors on a patent of this patch. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Sabab, Vediappan, Finnie, McAdam, Jukes, Vreugde and Wormald.)

Melt extrusion 3D printing has become an attractive additive manufacturing technology to construct degradable scaffolds as tissue precursors in order to create clinically relevant medical devices. Towards this end, a commonly used synthetic polyester, poly-caprolactone (PCL), was used to make scaffolds composed of different biomaterial compositions to increase bioactivity using 3D melt pneumatic extrusion technology. Varying ratios of the natural biopolymer, chitosan, or the bioceramic, β-tricalcium phosphate (TCP) were blended with PCL to fabricate support scaffolds with three-dimensional (3D) architecture for human bone-marrow derived mesenchymal stem cell (hBMSC) growth for potential bone regeneration application. In this study, basic printing requirements as well as biomaterial dynamic mechanical (DMA), elemental, and thermogravimetric (TGA) analysis results demonstrate material homogeneity as well as thermal stability. Scaffold morphology and microarchitecture were assessed using scanning electron microscopy (SEM) alongside in vitro scaffold degradation and biological characterisation. Human BMSC proliferation was assessed using fluorescence imaging, and quantitated via the 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) colorimetric assay. These in vitro cell viability studies revealed that the highest chitosan concentration blend of 20% favoured the most hBMSC growth, exhibited the most swelling, and showed minimal degradation after 28 days. The 20% TCP blend had the second highest hBMSC growth, exhibited moderate swelling, and the fastest degradation rate. Overall, this study demonstrates the first direct comparison of a natural biopolymer-based, that is, chitosan, 3D melt extruded PCL composite with that of a bioceramic-based, that is, β-TCP, PCL composite and their effects on hBMSC 3D proliferation. 3D melt extruded PCL-based composite scaffolds methodology offers a straightforward way to print scaffolds with good shape fidelity, interconnected porosities and enhanced bioactivity; and demonstrates their potential use for regenerative, bone repair applications., (© 2021 Wiley Periodicals LLC.)

The racemic title compound, [Fe(C 5 H 5 )(C 16 H 27 O 2 )], comprises an α,ω-diol-substituted undecyl chain with a ferrocenyl substituent at at one terminus. The alkane chain is inclined to the substituted ring of the ferrocene grouping by 84.22 (13)°. The ferrocene rings are almost eclipsed and parallel. The crystal structure features O-H⋯O and C-H⋯O hydrogen bonds and C-H⋯π contacts that stack the mol-ecules along the c- axis direction. A Hirshfeld surface analysis reveals that H⋯H inter-actions (83.2%) dominate the surface contacts., (© McAdam and Simpson 2022.)

Beta-chitin patch has previously been proven to be an effective haemostat, but whether modifying the patch affects its efficacy and safety, remains unanswered. In this study, the patch was modified using polyethylene oxide, Pluronic-F127, calcium, increased thickness or polyphosphate, and their effect on the process of haemostasis and cytotoxicity was tested and compared with standard-of-care, Surgicel and FloSeal. Whole blood collected from volunteers was applied to the patches to test their whole blood clotting and thrombin generation capacities, whilst platelet isolates were used to test their platelet aggregation ability. The fluid absorption capacity of the patches was tested using simulated body fluid. Cytotoxicity of the patches was tested using AlamarBlue assays and PC12 cells and the results were compared with the standard-of-care. In this study, beta-chitin patch modifications failed to improve its whole blood clotting, platelet aggregation and thrombin generation capacity. Compared to non-modified patch, modifications with polyethylene oxide or calcium reduced platelet aggregation and thrombin generation capacity, while increasing the thickness or adding polyphosphate decreased platelet aggregation capacity. The cytotoxicity assays demonstrated that the beta-chitin patches were non-toxic to cells. In vivo research is required to evaluate the safety and efficacy of the beta-chitin patches in a clinical setting., (© 2021. The Author(s).)

A 2,2'-bipyridine with bulky triphenylamine substituents in the 6 and 6' positions of the ligand (6,6'-ditriphenylamine-2,2'-bipyridine, 6,6'-diTPAbpy) was generated. Despite the steric bulk, the ligand readily formed bis(homoleptic) complexes with copper(I) and silver(I) ions. Unfortunately, efforts to use the 6,6'-diTPAbpy system to generate heteroleptic [Cu(6,6'-diTPAbpy)(bpy)] + complexes were unsuccessful with only the [Cu(6,6'-diTPAbpy) 2 ](PF 6 ) complex observed. The 6,6'-diTPAbpy ligand could also be reacted with 6-coordinate metal ions that featured small ancillary ligands, namely, the [Re(CO) 3 Cl] and [Ru(CO) 2 Cl 2 ] fragments. While the complexes could be formed in good yields, the steric bulk of the TPA units does alter the coordination geometry. This is most readily seen in the [(6,6'-diTPAbpy)Re(CO) 3 Cl] complex where the Re(I) ion is forced to sit 23° out of the plane formed by the bpy unit. The electrochemical and photophysical properties of the family of compounds were also examined. 6,6'-diTPAbpy exhibits a strong ILCT absorption band (356 nm, 50 mM -1 cm -1 ) which displays a small increase in intensity for the homoleptic complexes ([Cu(6,6'-diTPAbpy) 2 ] + ; 353 nm, 72 mM -1 cm -1 , [Ag(6,6'-diTPAbpy) 2 ] + ; 353 nm, 75 mM -1 cm -1 ), despite containing 2 equiv of the ligand, attributed to an increased dihedral angle between the TPA and bpy moieties. For the 6-coordinate complexes the ILCT band is further decreased in intensity and overlaps with MLCT bands, consistent with a further increased TPA-bpy dihedral angle. Emission from the 1 ILCT state is observed at 436 nm (τ = 4.4 ns) for 6,6'-diTPAbpy and does not shift for the Cu, Ag, and Re complexes, although an additional 3 MLCT emission is observed for [Re(6,6'-diTPAbpy)(CO) 3 Cl] (640 nm, τ = 13.8 ns). No emission was observed for [Ru(6,6'-diTPAbpy)(CO) 2 Cl 2 ]. Transient absorption measurements revealed the population of a 3 ILCT state for the Cu and Ag complexes (τ = 80 ns). All assignments were supported by TD-DFT calculations and resonance Raman spectroscopic measurements.

Three-dimensional (3D) bioprinting has emerged to create novel cell-based therapies for regenerative medicine applications. Vascularized networks within engineered constructs are required, and toward this end, we report a promising strategy using core-shell (c/s) extrusion 3D-bioprinting technology that employs biomimetic biomaterials to construct regenerative, prevascularized scaffolds for wound care. A custom-designed cell-responsive bioink consisting of a 13% (w/v) cell-laden gelatin methacryloyl (GelMA) shell surrounding a peptide-functionalized, succinylated chitosan (C)/dextran aldehyde (D) cell-laden core was successfully bioprinted resulting in organized microdesigns exhibiting excellent cell viability and subsequent vessel formation. Our templating strategy takes advantage of GelMA's intrinsic thermoreversible properties of low degree of acryloyl functionalization used in combination with a lightly, chemically cross-linked peptide-CD core to serve as temporal structural supports that stabilize during extrusion onto a cooled platform. Mechanical integrity was further strengthened layer-by-layer via GelMA UV photo-cross-linking. We report the first example of GelMA used in combination with a peptide-CD bioink to c/s 3D-bioprint regenerative, prevascularized constructs for wound care. Particular cell adhesion and proteolytic peptide-CD functionalized pair combinations, P15/MMP-2 and P15/cRGD, were found to significantly increase growth of human bone-marrow-derived mesenchymal stems cells (hBMSCs) and human umbilical vein endothelial cells (HUVECs). The constructs delivered two cell types: hBMSCs in the shell bioink and HUVECs within the core bioink. Cord-like, natural microvascularization was shown with endothelial cell marker expression as confirmed by immunofluorescence (IF) staining exhibiting tubelike structures. In addition, in vitro skin wound healing activity of the construct showed a ∼twofold rate of wound closure. Overall, c/s 3D-bioprinted, peptide-CD/GelMA constructs provided the appropriate microenvironment for in vitro stem and endothelial cell viability, delivery, and differentiation. We foresee these custom constructs as representing a fundamental step toward engineering larger scale regenerative, prevascularized tissues.

The photophysical properties of a series of rhenium(I) tricarbonyl and platinum(II) bis(acetylide) complexes containing a triphenylamine (TPA)-substituted 1,10-phenanthroline ligand have been examined. The complexes possess both metal-to-ligand charge-transfer (MLCT) and intraligand charge-transfer (ILCT) transitions that absorb in the visible region. The relative energies and ordering of the absorbing CT states have been successfully controlled by changing the metal center and modulating the donating ability of the TPA group through the addition of electron-donating methoxy and electron-withdrawing cyano groups. The ground-state properties behave in a predictable manner as a function of the TPA substituent and are characterized with a suite of techniques including electronic absorption spectroscopy, resonance Raman spectroscopy, electrochemistry, and time-dependent density functional theory calculations. However, systematic control over the ground-state properties of the complexes does not extend to their excited-state behavior. Unexpectedly, despite variation of both the MLCT and ILCT state energies, all of the luminescent complexes displayed near-isoenergetic emission at 298 K, yet the emissive lifetimes of the complexes vary from 290 ns to 3.9 μs. Excited-state techniques including transient absorption and transient resonance Raman, combined with a suite of quantum-chemical calculations, including scalar relativistic effects to elucidate competitive excited-state relaxation pathways, have been utilized to aid in assignment of the long-lived state in the complexes, which was shown to possess differing 3 MLCT and 3 ILCT contributions across the series.

Hydrogels with excellent mechanical properties were synthesized by radical photo-polymerization of three different types of ion-pair comonomers (IPC), without requiring any chemical cross-linking agent. Insoluble gels formed only at a specific solution concentration range, which was unique to the particular salt. The gels changed properties after one day soaking in water, becoming less stiff and more extendible, but remained stable after that. Strains of up to 4000% were measured for one salt pair and ultimate stresses of up to 2.53 MPa for another. Self-healing properties were noted along with some recovery of creep, due to the non-covalent nature of the gel. These properties arise through a combination of electrostatic and hydrophobic interactions of the polymer chains. Immersion of the gels in salt solution screened the electrostatic interactions, resulting in dissolution of the gel.

Low-voltage electrochemical actuation of radical polymer gels has been demonstrated in an organic electrolyte. Polymer gels were prepared by post-modification of active-ester precursor gels with an amine-functionalised radical. A combination of few-layer graphene and multiwall carbon nanotubes gave high conductivity and improved actuation in the gels, with 32% linear actuation. The actuator system showed good stability over at least 10 cycles, showing its promise. The cycle time was several hours due to mass-transport limited transport of ions and solvent into the device., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

The title salt, C 10 H 21 N 2 O + ·C 7 H 12 NO 4 S - , comprises a 3-methacryl-amido- N , N , N -tri-methyl-propan-1-aminium cation and a 2-acryl-amido-2-methyl-propane-1-sulfonate anion. The salt crystallizes with two unique cation-anion pairs in the asymmetric unit of the ortho-rhom-bic unit cell. The crystal studied was an inversion twin with a 0.52 (4):0.48 (4) domain ratio. In the crystal, the cations and anions stack along the b -axis direction and are linked by an extensive series of N-H⋯O and C-H⋯O hydrogen bonds, forming a three-dimensional network. Hirshfeld surface analysis was carried out on both the asymmetric unit and the two individual salts. The contribution of inter-atomic contacts to the surfaces of the individual cations and anions are also compared., (© Wickramasinhage et al. 2019.)

In the title compound, the asymmetric unit comprises an N , N , N -trimethyl-1-(4-vinyl-phen-yl)methanaminium cation and a 4-vinyl-benzene-sulfonate anion, C 12 H 18 N + ·C 8 H 7 O 3 S - . The salt has a polymerizable vinyl group attached to both the cation and the anion. The methanaminium and vinyl substituents on the benzene ring of the cation subtend angles of 86.6 (3) and 10.5 (9)° to the ring plane, while the anion is planar excluding the sulfonate O atoms. The vinyl substituent on the benzene ring of the cation is disordered over two sites with a refined occupancy ratio of 0.542 (11):0.458 (11). In the crystal, C-H⋯O hydrogen bonds dominate the packing and combine with a C-H⋯π(ring) contact to stack the cations and anions along the a -axis direction. Hirshfeld surface analysis of the salt and of the individual cation and anion components is also reported.

The self-assembly of ligands of different geometries with metal ions gives rise to metallosupramolecular architectures of differing structural types. The rotational flexibility of ferrocene allows for conformational diversity, and, as such, self-assembly processes with 1,1'-disubstituted ferrocene ligands could lead to a variety of interesting architectures. Herein, we report a small family of three bis-bidentate 1,1'-disubstituted ferrocene ligands, functionalized with either 2,2'-bipyridine or 2-pyridyl-1,2,3-triazole chelating units. The self-assembly of these ligands with the (usually) four-coordinate, diamagnetic metal ions Cu(I), Ag(I), and Pd(II) was examined using a range of techniques including 1 H and DOSY NMR spectroscopies, high-resolution electrospray ionization mass spectrometry, X-ray crystallography, and density functional theory calculations. Additionally, the electrochemical properties of these redox-active metallosupramolecular assemblies were examined using cyclic voltammetry and differential pulse voltammetry. The copper(I) complexes of the 1,1'-disubstituted ferrocene ligands were found to be coordination polymers, while the silver(I) and palladium(II) complexes formed discrete [1 + 1] or [2 + 2] metallomacrocyclic architectures.

Polyacrylamide gel electrophoresis is a universal tool in a biochemist's toolkit for protein and nucleic acid separation and subsequent visualisation and analysis. The standard formulation of polyacrylamide gels consists of acrylamide (ACM) monomer crosslinked with bisacrylamide (MBA) which creates a gel with excellent sieving properties but which is mechanically fragile and prone to tearing during post-electrophoresis manipulations involved in visualisation and analysis. By adding a poly(ethylene oxide) macro-crosslinker to the standard gel formulation, we have created a tough gel matrix that can be used to fractionate proteins and nucleic acids by polyacrylamide gel electrophoresis. The protein and nucleic acid resolving capabilities and performance during staining and electroblotting of the tough gel matrix rivals that of conventional acrylamide/bisacrylamide gels. The tough gel matrix is resistant to tear and remarkably elastic, capable of stretching to over four times its original length before breaking, and represents a significant improvement over standard polyacrylamide gel formulations., (© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A 2,2'-bipyridine-appended bis(ferrocene) three tiered molecular folding ruler, can be switched from a folded conformation to an extended conformation by the addition of [Cu(CH 3 CN) 4 ](PF 6 ) and 6,6'-dimesityl-2,2'-bipyridine. This extension and contraction process could be triggered either chemically or electrochemically and was reversible.

The wet and soft nature of hydrogels makes them useful as a mimic for biological tissues, and in uses such as actuators and drug delivery vehicles. For many applications the mechanical performance of the gel is critical, but gels are notoriously weak and prone to fracture. Free radical polymerization is a very powerful technique allowing for fine spatial and temporal control of polymerization, but also allows for the use of a wide range of monomers and mixtures. In this work, it is demonstrated that extremely tough and extensible hydrogels can be readily produced through simple radical polymerization of acrylamide or acrylic acid with a poly(ethylene oxide) macrocross-linker. These gels, with a water content of 85%, are extremely elastic with an extension much more than 15 000% at 9 MPa true stress. They can be compressed over 98% at a stress of 17 MPa. They are notch-insensitive, and the usual trouser tear test does not work because the tear simply does not propagate. This highly extensible nature seems to be related to very long chain lengths between cross-links and efficient incorporation of chains into the network., (© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The closely related title compounds, 3-(2,5-dimeth-oxy-3,4,6-tri-methyl-phen-yl)propyl methacrylate, C 18 H 26 O 4 (I), and 3-(2,4,5-trimethyl-3,6-dioxo-cyclo-hexa-1,4-dien-yl)propyl methacrylate, C 16 H 20 O 4 (II), are monomers suitable for the preparation of redox polymers. They consist of a propyl-methacrylate group and three methyl substituents on di-meth-oxy-benzene and quinone cores, respectively. Both crystal structures feature weak C-H⋯O hydrogen bonds and C-H⋯π(ring) contacts between methyl groups and the six-membered rings.

A new 2-pyridyl-1,2,3-triazole (pytri) ligand, TPA-pytri, substituted with a triphenylamine (TPA) donor group on the 5 position of the pyridyl unit was synthesized and characterized. Dichloroplatinum(II), bis(phenylacetylide)platinum(II), bromotricarbonylrhenium(I), and bis(bipyridyl)ruthenium(II) complexes of this ligand were synthesized and compared to complexes of pytri ligands without the TPA substituent. The complexes of unsubstituted pytri ligands show metal-to-ligand charge-transfer (MLCT) absorption bands involving the pytri ligand in the near-UV region. These transitions are complemented by intraligand charge-transfer (ILCT) bands in the TPA-pytri complexes, resulting in greatly improved visible absorption (λ max = 421 nm and ϵ = 19800 M -1 cm -1 for [Pt(TPA-pytri)Cl 2 ]). The resonance Raman enhancement patterns allow for assignment of these absorption bands. The [Re(TPA-pytri)(CO) 3 Br] and [Pt(TPA-pytri)(CCPh) 2 ] complexes were examined with time-resolved infrared spectroscopy. Shifts in the C≡C and C≡O stretching bands revealed that the complexes form states with increased electron density about their metal centers. [Pt(TPA-pytri)Cl 2 ] is unusual in that it is emissive despite the presence of deactivating d-d states, which prevents emission from the unsubstituted pytri complex.

A series of tris(homoleptic) ruthenium(II) complexes of 2-(1-R-1H-1,2,3-triazol-4-yl)pyridine "click" ligands (R-pytri) with various aliphatic (R = butyl, hexyl, octyl, dodecyl, and hexdecyl) and aromatic (R = phenyl and benzyl) substituents was synthesized in good yields (52%-66%). The [Ru(R-pytri) 3 ] 2+ (X - ) 2 complexes (where X - = PF 6 - or Cl - ) were characterized by elemental analysis, high-resolution electrospray ionization mass spectrometry (HR-ESI-MS), 1 H and 13 C nuclear magnetic resonance (NMR) and infrared (IR) spectroscopies, and the molecular structures of six of the compounds confirmed by X-ray crystallography. 1 H NMR analysis showed that the as-synthesized materials were a statistical mixture of the mer- and fac-[Ru(R-pytri) 3 ] 2+ complexes. These diastereomers were separated using column chromatography. The electronic structures of the mer- and fac-[Ru(R-pytri) 3 ] 2+ complexes were examined using ultraviolet-visible (UV-Vis) spectroscopy and cyclic and differential pulse voltammetry. The family of R-pytri ligands and the corresponding mer- and fac-[Ru(R-pytri) 3 ] 2+ complexes were tested for antimicrobial activity in vitro against both Staphylococcus aureus and Escherichia coli bacteria. Agar-based disk diffusion assays indicated that two of the [Ru(R-pytri) 3 ](X) 2 complexes (where X = PF 6 - and R = hexyl or octyl) displayed good antimicrobial activity against Gram-positive S. aureus and no activity against Gram-negative E. coli at the concentrations tested. The most active [Ru(R-pytri) 3 ] 2+ complexes ([Ru(hexpytri) 3 ] 2+ and Ru(octpytri) 3 ] 2+ ) were converted to the water-soluble chloride salts and screened for their activity against a wider range of pathogenic bacteria. As with the preliminary screen, the complexes showed good activity against a variety of Gram-positive strains (minimum inhibitory concentration (MIC) = 1-8 μg/mL) but were less effective against Gram-negative bacteria (MIC = 16-128 μg/mL). Most interestingly, in some cases, the ruthenium(II) "click" complexes proved more active (MIC = 4-8 μg/mL) than the gentamicin control (MIC = 16 μg/mL) against two strains of methicillin-resistant S. aureus (MRSA) (MR 4393 and MR 4549). Transmission electron microscopy (TEM) experiments and propidium iodide assays suggested that the main mode of action for the ruthenium(II) R-pytri complexes was cell wall/cytoplasmic membrane disruption. Cytotoxicity experiments on human dermal keratinocyte and Vero (African green monkey kidney epithelial) cell lines suggested that the complexes were only modestly cytotoxic at concentrations well above the MIC values.

A series of [Co(III)(N4Py)(X)](ClO4)n (X = Cl(-), Br(-), OH(-), N3(-), NCS(-)-κN, n = 2: X = OH2, NCMe, DMSO-κO, n = 3) complexes containing the tetrapyridyl N5 ligand N4Py (N4Py = 1,1-di(pyridin-2-yl)-N,N-bis(pyridin-2-ylmethyl)methanamine) has been prepared and fully characterized by infrared (IR), UV-visible, and NMR spectroscopies, high-resolution electrospray ionization mass spectrometry (HRESI-MS), elemental analysis, X-ray crystallography, and electrochemistry. The reduced Co(II) and Co(I) species of these complexes have been also generated by bulk electrolyses in MeCN and characterized by UV-visible and EPR spectroscopies. All tested complexes are catalysts for the photocatalytic production of H2 from water at pH 4.0 in the presence of ascorbic acid/ascorbate, using [Ru(bpy)3](2+) as a photosensitizer, and all display similar H2-evolving activities. Detailed mechanistic studies show that while the complexes retain the monodentate X ligand upon electrochemical reduction to Co(II) species in MeCN solution, in aqueous solution, upon reduction by ascorbate (photocatalytic conditions), [Co(II)(N4Py)(HA)](+) is formed in all cases and is the precursor to the Co(I) species which presumably reacts with a proton. These results are in accordance with the fact that the H2-evolving activity does not depend on the chemical nature of the monodentate ligand and differ from those previously reported for similar complexes. The catalytic activity of this series of complexes in terms of turnover number versus catalyst (TONCat) was also found to be dependent on the catalyst concentration, with the highest value of 230 TONCat at 5 × 10(-6) M. As revealed by nanosecond transient absorption spectroscopy measurements, the first electron-transfer steps of the photocatalytic mechanism involve a reductive quenching of the excited state of [Ru(bpy)3](2+) by ascorbate followed by an electron transfer from [Ru(II)(bpy)2(bpy(•-))](+) to the [Co(II)(N4Py)(HA)](+) catalyst. The reduced catalyst then enters into the H2-evolution cycle.

The photophysics of a family of exo-functionalized [Pd2L4](4+) metallo-supramolecular cage architectures constructed from a tripyridyl 1,2,3-triazole backbone are reported. Several spectroscopic techniques are employed including both electronic (steady-state and transient absorption and emission) and vibrational (resonant and nonresonant Raman) methods. These experimental results are interpreted alongside simulated results from density functional theory calculations of the system's vibrational and electronic properties. The ligands and cages are shown to be essentially insulated from the exo-functionalization. They exhibit electronic transitions in the UV region and excited-state properties that are little affected by formation of the cage. Upon functionalization, characteristic Raman bands, electronic transitions, and emission bands associated with, and confined to, the substituent are observed.

Electroactive metallocene polymers are of interest due to the possibility that they offer a muscle-like response, and in gel systems very large volume changes are possible. The ferrocenyl moiety exhibits physical and electrochemical stability of the neutral and oxidized forms and could be a candidate for use as the redox-active group in these materials. The title compounds, [Fe(C5H5)(C10H11O2)], (I), and [Fe(C10H11O2)2], (II), comprise a typical ferrocene core with coplanar and approximately eclipsed cyclopentadienyl (Cp) rings. In (I), there is a single methyl methacrylate substituent, with the other Cp ring unsubstituted. In (II), a methyl methacrylate substituent on each Cp ring completes the structure. In both compounds, there is an s-trans geometry of the vinyl and carbonyl components of the methacrylate group. Inversion dimers formed through C-H...O contacts dominate the crystal packing of both molecules. Weak C-H...π(ring) contacts and, in the case of (I), an unusual C-H...π(alkene) contact further stabilize the structures.

The isomeric derivatives 1,2-bis-(iodo-meth-yl)benzene, (I), and 1,3-bis-(iodo-meth-yl)benzene (II), both C8H8I2, were prepared by metathesis from their di-bromo analogues. The ortho-derivative, (I), lies about a crystallographic twofold axis that bis-ects the C-C bond between the two iodo-methyl substituents. The packing in (I) relies solely on C-H⋯I hydrogen bonds supported by weak parallel slipped π-π stacking inter-actions [inter-centroid distance = 4.0569 (11) Å, inter-planar distance = 3.3789 (8) Å and slippage = 2.245 Å]. While C-H⋯I hydrogen bonds are also found in the packing of (II), type II, I⋯I halogen bonds [I⋯I = 3.8662 (2) Å] and C-H⋯π contacts feature prominently in stabilizing the three-dimensional structure.

The closely related title compounds, 4-acrylamido-2,2,6,6-tetramethylpiperidine-1-oxyl, C12H21N2O2, (I), and N-(2,2,6,6-tetramethylpiperidin-4-yl)acrylamide monohydrate, C12H22N2O·H2O, (II), are important monomers in the preparation of redox-active polymers. They comprise an acrylamide group of the usual s-cis configuration appended to a 2,2,6,6-tetramethyl-substituted piperidine-1-oxyl radical or a piperidinyl chair, respectively. The adjacent amide and piperidinyl H atoms are approximately trans across the C-N bond. The packing in (I) is dominated by N-H...O hydrogen bonds; these are supported by C-H...O contacts to form an R2(1)(6) ring repeat, a motif which has been observed in other acrylamide structures. In (II), hydrogen bonds are again key to the packing arrangements. In this case, the incorporated solvent water molecule acts as an acceptor through its O atom and as a donor through both H atoms, binding three adjacent piperidinylacrylamide molecules into layers. In both structures, weak C-H...O contacts involving the piperidinyl methyl H atoms and a proximal acrylamide carbonyl O atom extend the structure in the third dimension.

The title compound, C16H10, crystallizes with four unique mol-ecules, designated 1-4, in the asymmetric unit of the monoclinic unit cell. None of the mol-ecules is planar, with the benzene rings of mol-ecules 1-4 inclined to one another at angles of 42.41 (4), 24.07 (6), 42.59 (4) and 46.88 (4)°, respectively. In the crystal, weak C-H⋯π(ring) interactions, augmented by even weaker C C-H⋯π(alkyne) contacts, generate a three-dimensional network structure with inter-linked columns of mol-ecules formed along the c-axis direction.

A 2,2'-bipyridine-appended ferrocene rotor, 1,1'-di(5-yl-ethynyl-2,2'-bipyridine)ferrocene, can be switched from a folded/stacked (syn) conformation to an extended/unstacked (anti) conformation by the addition of [Cu(CH3CN)4](PF6) and 6,6'-dimesityl-2,2'-bipyridine. This extension and contraction process was completely reversible and could be triggered either chemically or electrochemically.

Two inverse 2-pyridyl-1,2,3-triazole "click" ligands, 2-(4-phenyl-1H-1,2,3-triazol-1-yl)pyridine and 2-(4-benzyl-1H-1,2,3-triazol-1-yl)pyridine, and their palladium(II), platinum(II), rhenium(I), and ruthenium(II) complexes have been synthesized in good to excellent yields. The properties of these inverse "click" complexes have been compared to the isomeric regular compounds using a variety of techniques. X-ray crystallographic analysis shows that the regular and inverse complexes are structurally very similar. However, the chemical and physical properties of the isomers are quite different. Ligand exchange studies and density functional theory (DFT) calculations indicate that metal complexes of the regular 2-(1-R-1H-1,2,3-triazol-4-yl)pyridine (R = phenyl, benzyl) ligands are more stable than those formed with the inverse 2-(4-R-1H-1,2,3-triazol-1-yl)pyridine (R = phenyl, benzyl) "click" chelators. Additionally, the bis-2,2'-bipyridine (bpy) ruthenium(II) complexes of the "click" chelators have been shown to have short excited state lifetimes, which in the inverse triazole case, resulted in ejection of the 2-pyridyl-1,2,3-triazole ligand from the complex. Under identical conditions, the isomeric regular 2-pyridyl-1,2,3-triazole ruthenium(II) bpy complexes are photochemically inert. The absorption spectra of the inverse rhenium(I) and platinum(II) complexes are red-shifted compared to the regular compounds. It is shown that conjugation between the substituent group R and triazolyl unit has a negligible effect on the photophysical properties of the complexes. The inverse rhenium(I) complexes have large Stokes shifts, long metal-to-ligand charge transfer (MLCT) excited state lifetimes, and respectable quantum yields which are relatively solvent insensitive.

The title compound, C12H20NO2, was synthesized from 4-hy-droxy-2,2,6,6-tetra-methyl-piperidin-1-oxyl (hy-droxy-TEMPO) and propargyl bromide. The six-membered ring adopts a flattened chair conformation and carries a propyn-yloxy substituent in an equatorial orientation at the 4-position. The N-O bond length of the piperidin-1-oxyl unit is 1.289 (3) Å. In the crystal, C-H⋯O hydrogen bonds combine with unusual C-H⋯π inter-actions involving the alkyne unit as acceptor to generate a three-dimensional network.

The title compounds, [Co2(C8H11BrO3)(CO)6], (1), and [Co2(C12H16Br2O4)(CO)6], (2), result from the replacement of two carbonyl ligands from dicobalt octa-carbonyl by the alkynes 4-hy-droxy-but-2-ynyl 2-bromo-2-methyl-propano-ate and but-2-yne-1,4-diyl bis-(2-bromo-2-methyl-propano-ate), respectively. Both mol-ecules have classic tetra-hedral C2Co2 cluster cores with the Co(II) atoms in a highly distorted octa-hedral coordination geometry. The alkyne ligands both adopt a cis-bent conformation on coordination. In the crystal structure of (1), classical O-H⋯O and non-classical C-H⋯O contacts form inversion dimers. These combine with weak O⋯O and Br⋯O contacts to stack the mol-ecules into inter-connected columns along the b-axis direction. C-H⋯O and C-H⋯Br contacts stabilize the packing for (2), and a weak Br⋯O contact is also observed. Inter-connected columns of mol-ecules again form along the b-axis direction.

Herein we describe a CuAAC "click" methodology for exo-functionalisation of Pd2L4 metallosupramolecular architectures. The potentially coordinating 1,2,3-triazole does not affect formation of the desired discrete complexes, nor does this external functional decoration affect the cisplatin-binding ability of the interior cavity of the assembly.

The title compounds, C11H11BrO3, (I), and C11H11NO5, (II), respectively, are derivatives of 6-hydroxy-5,7,8-trimethylchroman-2-one substituted at the 5-position by a Br atom in (I) and by a nitro group in (II). The pyranone rings in both molecules adopt half-chair conformations, and intramolecular O-H···Br [in (I)] and O-H···O(nitro) [in (II)] hydrogen bonds affect the dispositions of the hydroxy groups. Classical intermolecular O-H···O hydrogen bonds are found in both molecules but play quite dissimilar roles in the crystal structures. In (I), O-H···O hydrogen bonds form zigzag C(9) chains of molecules along the a axis. Because of the tetragonal symmetry, similar chains also form along b. In (II), however, similar contacts involving an O atom of the nitro group form inversion dimers and generate R2(2)(12) rings. These also result in a close intermolecular O···O contact of 2.686 (4) Å. For (I), four additional C-H···O hydrogen bonds combine with π-π stacking interactions between the benzene rings to build an extensive three-dimensional network with molecules stacked along the c axis. The packing in (II) is much simpler and centres on the inversion dimers formed through O-H···O contacts. These dimers are stacked through additional C-H···O hydrogen bonds, and further weak C-H···O interactions generate a three-dimensional network of dimer stacks.

1,5-Diarylbiguanides, where the aryl groups are phenyl (HL1), 3,5-dimethylphenyl (HL2), 3,5-dimethoxyphenyl (HL3), 4-t-butylphenyl (HL4) or 4-bromophenyl (HL5), have been prepared and characterised. HL3 and HL5 have been structurally characterised by X-ray crystallography, which shows them to adopt the expected tautomeric form for biguanides. They have extensive hydrogen-bonding interactions in the solid state, involving the biguanide NH groups supported by, in the case of HL3, the OCH3 aryl substituents or, in the case of HL5, Br···Br interactions. Reactions of HL1–HL4 with Ni(BF4)2 gives complexes of the type [Ni(HL)2](BF4)2, while reactions of HL1–HL4 with Ni(BF4)2 and triethylamine give neutral complexes of the type [Ni(L)2], where the biguanide ligand has been deprotonated at the N(ring) nitrogen. Both series of complexes were characterised in solution and the solid state. Cyclic voltammetry shows a largely irreversible Ni(II)/Ni(III) oxidation which becomes easier by ca. 70 mV upon ligand deprotonation, with more subtle variations resulting from the changes in aryl ring substituents. Infrared and 1H NMR spectroscopies both provide evidence for ligand deprotonation leading to the chelate ring becoming increasingly aromatised. X-ray crystallographic analyses of five of the complexes also show changes in bond lengths and angles within the chelate ring, consistent with increased electron delocalisation. A variety of hydrogen bonding motifs involving the complex ions, counterions and solvent molecules are found. The results of DFT calculations on both cationic and neutral complexes provide calculated structures consistent with the experimental ones and these, along with the results of vibrational spectroscopic studies, provide further evidence for increased aromatisation upon deprotonation. The potential for the complexes to act as tectons for the rational assembly of hydrogen bonded metallosupramolecules is discussed and the X-ray structure of such an assembly, between [Ni(L3)2] and 1,8-naphthalimide, is presented.

The syntheses of the 4-n-propyl and 4-phenyl substituted fac-Re(CO)(3) complexes of the tridentate "click" ligand (2,6-bis(4-substituted-1,2,3-triazol-1-ylmethyl)pyridine) are described. The complexes were obtained by refluxing methanol solutions of [Re(CO)(5)Cl], AgPF(6) and either the 4-propyl or 4-phenyl substituted ligand for 16 h. The ligands and the two rhenium(I) complexes were characterised by elemental analysis, HR-ESMS, ATR-IR, (1)H and (13)C NMR spectroscopy and the molecular structures of both complexes were confirmed by X-ray crystallography. The electronic structure of the fac-Re(CO)(3) "click" complexes was probed using UV-Vis, Raman and emission spectroscopy, cyclic voltammetry and DFT calculations. Altering the electronic nature of the ligand's substituent, from aromatic to alkyl, had little effect on the absorption/emission maxima and electrochemical properties of the complexes indicating that the 1,2,3-triazole unit may insulate the metal centre from the electronic modification at the ligands' periphery. Both Re(I) complexes were found to be weakly emitting with short excited state lifetimes. The electrochemistry of the complexes is defined by quasi-reversible Re oxidation and irreversible triazole-based ligand reduction processes.

The title compound, C(11)H(12)O(3), is essentially planar, with an r.m.s. deviation of 0.179 Å from the mean plane through the 14 non-H atoms in the mol-ecule. The benzene ring and the pyranone mean plane are inclined at 13.12 (6)° to one another and the pyran-one ring adopts a flattened chair conformation. In the crystal, O-H⋯O hydrogen bonds and C-H⋯O contacts form R(1) (2)(6) rings and link mol-ecules into chains along b. Additional C-H⋯O contacts generate inversion dimers, with R(2) (2)(8) ring motifs, and form sheets parallel to (-102) which are linked by C-H⋯π interactions.

The title mol-ecule, C(14)H(14)O(4), lies on a twofold rotation axis that bis-ects the central benzene ring, with only one half-mol-ecule in the asymmetric unit. The pyran-one systems adopt distorted twist- boat conformations, with the two methyl-ene C atoms displaced by 0.537 (1) and 0.163 (2) Å from the best-fit plane through the remaining five C and O atoms (r.m.s. deviation = 0.073 Å). In the crystal, bifurcated C-H⋯(O,O) hydrogen bonds link pairs of adjacent mol-ecules in an obverse fashion, stacking mol-ecules along c. These contacts are further stabilized by very weak π-π inter-actions between adjacent benzene rings with centroid-centroid distances of 4.1951 (4) Å. Additional C-H⋯O contacts link these stacks, giving a three-dimensional network.

The title compound, C(15)H(24)N(2)O(2), crystallizes with two unique mol-ecules, (I) and (II), in the asymmetric unit, differing in the orientation of the acryloyl units with respect to the piperidine rings. The acryl-amide units are essentially planar in both mol-ecules (r.m.s. deviations = 0.042 and 0.024 Å, respectively), as are the C(3)N chains of the acryloyl units. The carbonyl O atoms of the acryloyl systems lie significantly out of these planes, viz. by -0.171 (9) Å for molecule (I) and by 0.33 (1) Å for molecule (II). The acryl-amide and acryloyl planes are inclined at 68.7 (4)° and 59.8 (3)° in the two mol-ecules. The piperidine rings each adopt twist boat conformations. In the crystal, strong N-H⋯O hydrogen bonds link the mol-ecules into zigzag C(4) chains along b. Additional C-H⋯O contacts result in the formation of stacks along a.

In the title mol-ecule, C(16)H(14)O(4)S, the dihydro-cyclo-penta-thio-phenone ring system is almost planar, with an r.m.s. deviation of 0.060 Å from the best fit plane through all nine non-H atoms. The cyclo-penta-none ring adopts a severely flattened envelope conformation with the C atom carrying the OH and ethylcarboxylate substituents at the flap. This atom lies only 0.185 (3) Å from the plane through the other four C atoms. The phenyl substituent is inclined at 43.37 (5)° to the dihydro-cyclo-penta-thio-phenone mean plane. In the crystal, mol-ecules are linked by pairs of O-H⋯O hydrogen bonds, forming inversion dimers with R(2) (2)(10) ring motifs. Weak C-H⋯O hydrogen bonds also link mol-ecules into chains along c, while an approximately orthogonal set of C-H⋯O contacts form chains along b, resulting in layers lying parallel to (100). Inversion dimers also form through weaker R(2) (2)(12) C-H⋯S contacts, which combine with C-H⋯O contacts to form stacks along b.

In the title mol-ecule, C(11)H(11)ClO(3), the fused pyran ring adopts a half-chair conformation. In the crystal, inter-molecular O-H⋯O hydrogen bonds link mol-ecules into chains along [100]. These chains are inter-connected by weak inter-molecular C-H⋯O contacts which generate R(2) (2)(8) ring motifs, forming sheets parallel to (001). Tetra-gonal symmetry generates an equivalent motif along b. Furthermore, the sheets are linked along the c axis by offset π-π stacking inter-actions involving the benzene rings of adjacent mol-ecules [with centroid-centroid distances of 3.839 (2) Å], together with an additional weak C-H⋯O hydrogen bond, resulting in an overall three-dimensional network.

The Cu(I)-catalyzed 1,3-cycloaddition of organic azides with terminal alkynes, the CuAAC "click" reaction is currently receiving considerable attention as a mild, modular method for the generation of functionalized ligand scaffolds. Herein we show that mild one-pot "click" methods can be used to readily and rapidly synthesize a family of functionalized bidentate 2-pyridyl-1,2,3-triazole ligands, containing electrochemically, photochemically, and biologically active functional groups in good to excellent yields (47-94%). The new ligands have been fully characterized by elemental analysis, HR-ESI-MS, IR, (1)H and (13)C NMR and in three cases by X-ray crystallography. Furthermore we have demonstrated that this family of functionalized "click" ligands readily form bis-bidentate Pd(II) complexes. Solution studies, X-ray crystallography, and density functional theory (DFT) calculations indicate that the Pd(II) complexes formed with the 2-(1-R-1H-1,2,3-triazol-4-yl)pyridine series of ligands are more stable than those formed with the [4-R-1H-1,2,3-triazol-1-yl)methyl]pyridine "click" ligands., (© 2011 American Chemical Society)

The title compound, C(12)H(14)O(3), consists of a chromanone unit with an -OH substituent at the 4-position and methyl substituents on the remaining C atoms of the aromatic ring. The fused pyran-one ring adopts a distorted envelope conformation with the methyl-ene group adjacent to the carbonyl carbon as the flap atom. The crystal structure is stabilized by classical O-H⋯O hydrogen bonds and weak C-H⋯O and C-H⋯π inter-actions, generating a three-dimensional network.

In the title compound, [Co(C(13)H(9))(C(28)H(20))], the Co atom is sandwiched between cyclo-penta-dienyl and cyclo-butadienyl rings that are inclined at a dihedral angle of 2.6 (3)°. The four phenyl rings are tilted with respect to the cyclo-butadienyl plane so that the C(4)Ph(4) unit constitutes a four-bladed propeller. The phenyl ring of the phenyl-alkyne substituent is inclined to the cyclo-penta-dienyl ring at an angle of 34.92 (18)°. The crystal structure is stabilized solely by C-H⋯π inter-actions which generate a three-dimensional network.

The centrosymmetric title compound, C(8)H(8)I(2), was prepared by metathesis from the dibromo analogue. In the crystal structure, weak C-H⋯I inter-actions link the mol-ecules into stacks down the b axis. The structure is further stabilized by short I⋯I contacts [3.8433 (2) Å], forming undulating sheets in the (101) plane.

N-(2-Bromoethyl)-4-piperidino-1,8-naphthalimide, C(19)H(19)BrN(2)O(2), (I), and N-(3-bromopropyl)-4-piperidino-1,8-naphthalimide, C(20)H(21)BrN(2)O(2), (II), are an homologous pair of 1,8-naphthalimide derivatives. The naphthalimide units are planar and each piperidine substituent adopts a chair conformation. This study emphasizes the importance of pi-stacking interactions, often augmented by other contacts, in determining the crystal structures of 1,8-naphthalimide derivatives.

The asymmetric unit of the title compound, [FeCo(2)(C(5)H(5))(2)(C(3)H(3)S(3))S(C(18)H(15)P)(CO)]CF(3)SO(3), consists of a triangular irondicobalt cluster cation and a trifluoro-methane-sulfonate anion. In the cation, the FeCo(2) triangle is symmetrically capped on one face by an S atom and on the other by a C atom linked to a methyl trithio-carbonate residue that bridges the Fe-C bond. Each Co atom carries a cyclo-penta-dienyl ligand while the Fe atom coordinates to one carbonyl and one triphenyl-phosphine ligand. In the crystal structure, the cation is linked to the anion by a number of weak non-classical C-H⋯O and C-H⋯F hydrogen bonds and weak S⋯O (3.317 Å) and S⋯F (3.198 Å) inter-actions. The structure is further stabilized by additional inter-molecular C-H⋯O, C-H⋯F and O⋯O (2.942 Å) contacts, together with an unusual S⋯π(Cp) inter-action (S⋯centroid distance = 3.385 Å), generating an extended network.