Dimeric Building Blocks Research Articles

Regioselective Oxidative Phenol Coupling by a Mushroom Unspecific Peroxygenase.

Bioactive dimeric (pre-)anthraquinones are ubiquitous in nature and are found in bacteria, fungi, insects, and plants. Their biosynthesis via oxidative phenol coupling (OPC) is catalyzed by cytochrome P450 enzymes, peroxidases, or laccases. While the biocatalysis of OPC in molds (Ascomycota) is well-known, the respective enzymes in mushroom-forming fungi (Basidiomycota) are unknown. Here, we report on the biosynthesis of the atropisomers phlegmacin A1 and B1 of the mushroom Cortinarius odorifer. The biosynthesis of these unsymmetrically 7,10'-homo-coupled dihydroanthracenones was heterologously reconstituted in the mold Aspergillus niger. Methylation of the parental monomer atrochrysone to its 6-O-methyl ether torosachrysone by the O-methyltransferase CoOMT1 precedes the regioselective homocoupling to phlegmacin, catalyzed by the enzyme CoUPO1 annotated as an "unspecific peroxygenase" (UPO). Our results reveal an unprecedented UPO reaction, thereby expanding the biocatalytic portfolio of oxidative phenol coupling beyond the commonly reported enzymes. The results show that Basidiomycota use peroxygenases to selectively couple aryls independently of and convergently to any other group of organisms, emphasizing the central role of OPC in natural processes.

A Cascade Reaction Triggered by H‐H Steric Hindrance: Dimeric Covalent Organic Frameworks on Au(111) and Dimeric Nanoribbons on Ag(111)

Comprehensive SummaryIn on‐surface synthesis, dimers are typically utilized to explore reaction mechanisms or as intermediates in the formation of final products. However, constructing the innovative nanostructures with dimers as building blocks remains challenging. Here, using non‐planar 2,2′,7,7′‐tetrabromo‐9,9′‐biflurenyliden molecules, we have successfully synthesized dimeric covalent organic frameworks (COFs) on the Au(111) surface through a temperature‐controlled cascade reaction. Notably, the H‐H steric hindrance within precursors caused by double bonds leads to selective stepwise debromination during the thermal annealing, which promotes the dimerization through intermolecular Ullmann coupling and cyclodehydrogenation reaction to form COFs primarily constituted by dimer building blocks. Combining scanning tunneling microscopy/spectroscopy and density functional theory calculations, we have precisely confirmed the structural evolution and reaction mechanism. Furthermore, by introducing Ag adatoms to form C−Ag−C intermediates, we have successfully regulated the reaction path and synthesized one‐dimensional nanoribbons with dimers as building blocks. This work not only validates the strategy of synthesizing dimeric nanostructures on different surfaces through cascade reactions induced by precursor design, but also enriches the research field of surface synthesis of COFs and nanoribbons.

HspB5 Chaperone Structure and Activity Are Modulated by Chemical-Scale Interactions in the ACD Dimer Interface.

Small heat shock proteins (sHsps) are a family of ATP-independent molecular chaperones that function as "holdases" and prevent protein aggregation due to changes in temperature, pH, or oxidation state. sHsps have a conserved α-crystallin domain (ACD), which forms the dimer building block, flanked by variable N- and C-terminal regions. sHsps populate various oligomeric states as a function of their sequestrase activity, and these dynamic structural features allow the proteins to interact with a plethora of cellular substrates. However, the molecular mechanisms of their dynamic conformational assembly and the interactions with various substrates remains unclear. Therefore, it is important to gain insight into the underlying physicochemical properties that influence sHsp structure in an effort to understand their mechanism(s) of action. We evaluated several disease-relevant mutations, D109A, F113Y, R116C, R120G, and R120C, in the ACD of HspB5 for changes to in vitro chaperone activity relative to that of wildtype. Structural characteristics were also evaluated by ANS fluorescence and CD spectroscopy. Our results indicated that mutation Y113F is an efficient holdase, while D109A and R120G, which are found in patients with myofibrillar myopathy and cataracts, respectively, exhibit a large reduction in holdase activity in a chaperone-like light-scattering assay, which indicated alterations in substrate-sHsp interactions. The extent of the reductions in chaperone activities are different among the mutants and specific to the substrate protein, suggesting that while sHsps are able to interact with many substrates, specific interactions provide selectivity for some substrates compared to others. This work is consistent with a model for chaperone activity where key electrostatic interactions in the sHsp dimer provide structural stability and influence both higher-order sHsp interactions and facilitate interactions with substrate proteins that define chaperone holdase activity.

Response to oxidative stress generation in Rhodotorula glutinis and Candida tropicalis by thallium dithiocarbamate complexes

Sodium diethyldithiocarbamate trihydrate (NaEt2dtc·3H2O) and sodium piperidine dithiocarbamate monohydrate (NaPidtc·H2O) reacted with thallium(I) carbonate to produce the complexes [Tl2(Et2dtc)2] C1 and [Tl2(Pidtc)2] C2. X-ray crystallographic analysis of the complexes elucidated their triclinic P-1 and monoclinic P21/n space groups, respectively, in addition to chelation via SS atoms from the uninegative ligands. Further, this analysis revealed the complexes' assembly as one-dimensional polymers of dimeric building blocks. The complexes (50 µg/ml) caused greater growth inhibitions in two pathogenic yeasts comparing with the ligand salts and cycloheximide. The ligand salts, respectively, inhibited R. glutinis with 15.02 and 15.14 % and C. tropicalis with 11.09 and 11.45 %, while cycloheximide, C1 and C2 offered inhibitions with 26.16, 38.9 and 46.4 % in R. glutinis and 13.4, 29.8 and 38.9 % in C. tropicalis, respectively. Further, the thallium complexes significantly affected the yeasts' soluble proteins {cycloheximide, C1 and C2 afforded 7.06 ± 0.05, 6.11 ± 0.08 and 5.43 ± 0.05 mg/g fresh weight (for R. glutinis) and 7.67 ± 0.15, 7.26 ± 0.06 and 6.025 ± 0.14 mg/g fresh weight (for C. tropicalis)} and total antioxidants {cycloheximide, C1 and C2 afforded 10.15 ± 0.21, 11.27 ± 0.16 and 14.97 ± 1.3 mg/g protein (for R. glutinis) and 19.4 ± 0.65, 16.0 ± 0.24 and 17.19 ± 0.55 mg/g protein (for C. tropicalis)} in addition to the catalase and peroxidase enzyme activities.

The self-assembly and structural regulation of a hydrogen-bonded dimeric building block formed by two N[sbnd]H···O hydrogen bonds on HOPG

The self-assembled behavior of an unsymmetric molecule (BCDTDA) with one imidazole group as center and benzoic acid group as functional group is studied, and the regulatory behaviors of coronene (COR) and three bipyridine derivatives (named BP, PEBP-C4 and PEBP-C8) on BCDTDA self-assembly structures are also investigated. Based on highly oriented pyrolytic graphite (HOPG) substrate, scanning tunneling microscopy (STM) is used to observe the variation of assembled behaviors at the solid-liquid interface. Because of the concentration effect, BCDTDA molecules can assemble into grids and Kagomés structures in the form of NH···O hydrogen bonded dimers. BCDTDA molecules still maintain dimeric structures in the regulation of COR and BP molecules to BCDTDA self-assembly. However, PEBP-C4 and PEBP-C8 destroy the structure of the dimers, and form a variety of co-assembled structures with BCDTDA. Different guest molecules coordinate the host molecules differently, which makes the experiment more meaningful. Combined with density functional theory (DFT) calculation, the discovery of molecular interactions provides a promising strategy for the construction of functional nanostructures and devices.

Directed Self-Assembly of Dimeric Building Blocks into Networklike Protein Origami to Construct Hydrogels.

Engineering proteins to construct self-assemblies is of crucial significance not only for understanding the sophisticated living systems but also for fabricating advanced materials with unexplored functions. However, due to the inherent chemical heterogeneity and structural complexity of the protein surface, designing complex protein assemblies in an anisotropic fashion remains challenging. Here, we describe a self-assembly approach to fabricating protein origami with a networklike structure by designing dual noncovalent interactions on the different positions of a single protein building block. With dimeric proteins as building blocks, 1D protein filaments were constructed by the designed metal coordination at key protein interfaces. Subsequently, the network superstructures were created by the cross-linking of the 1D protein filaments at branch point linkages through the second designed π-π stacking interactions. Notably, upon increasing the protein concentration, the formed protein networks convert into hydrogels with reversible, injectable, and self-healing properties, which have the ability to promote bone regeneration. This strategy could be used to fabricate other protein-based materials with unexplored functions.

Modular nucleic acid scaffolds for synthesizing monodisperse and sequence-encoded antibody oligomers

Synthesizing protein oligomers that contain exact numbers of multiple different proteins in defined architectures is challenging. DNA-DNA interactions can be used to program protein assembly into oligomers; however, existing methods require changes to DNA design to achieve different numbers and oligomeric sequences of proteins. Herein, we develop a modular DNA scaffold that uses only six synthetic oligonucleotides to organize proteins into defined oligomers. As a proof-of-concept, model proteins (antibodies) are oligomerized into dimers and trimers, where antibody function is retained. Illustrating the modularity of this technique, dimer and trimer building blocks are then assembled into pentamers containing three different antibodies in an exact stoichiometry and oligomeric sequence. In sum, this report describes a generalizable method for organizing proteins into monodisperse, sequence-encoded oligomers using DNA. This advance will enable studies into how oligomeric protein sequences affect material properties in areas spanning pharmaceutical development, cascade catalysis, synthetic photosynthesis, and membrane transport.

In silico and in vitro mapping of specificity patterns of glycosaminoglycans towards cysteine cathepsins B, L, K, S and V

Human cysteine cathepsins are lysosomal proteases, which are involved in different biological processes. Their enzymatic activity can be regulated by glycosaminoglycans (GAGs): long linear periodic negatively charged polysaccharides, which dimeric building blocks consist of uronic acid and hexosamine monosaccharide units. In this study, molecular docking simulations of chondroitin 4-sulfate, chondroitin 6-sulfate, heparin, heparan sulfate, dermatan sulfate and hyaluronic acid of various chain lengths were performed with cathepsins B, L, K, S and V and followed by molecular dynamics-based refinement and binding free energy analysis. We concluded that electrostatics might be a driving force for cathepsin-GAG interactions; indeed as in most of characterised systems, the increase of GAG chain length consequently leads to a more pronounced effect on the strength of cathepsin-GAG interactions. Results also suggest that binding of GAGs at different regions on cathepsins surface affect differently their enzymatic activity and could is dependent on cathepsin and GAG type. Present data contribute to systematic description of cathepsin-GAG interactions, which is helpful in understanding the subtle molecular mechanisms of protease regulation behind their biological functions.

The Self-Assembly and Structural Regulation of a Hydrogen-Bonded Dimeric Building Block Formed by Two N-H⋯O Hydrogen Bonds on HOPG

The Self-Assembly and Structural Regulation of a Hydrogen-Bonded Dimeric Building Block Formed by Two N-H⋯O Hydrogen Bonds on HOPG

The self-assembly and pyridine regulation of a hydrogen-bonded dimeric building block formed by a low-symmetric aromatic carboxylic acid.

The supramolecular self-assembly behavior of a low-symmetric aromatic carboxylic acid molecule (H5BHB) and its co-assembly behavior with a series of pyridine molecules (BPD, BPDYB and TPDYB) were studied at the heptanoic acid/HOPG liquid-solid interface. Scanning tunneling microscopy (STM) observations revealed that H5BHB molecules tend to form dimeric building blocks which then assemble into a close-packed structure. BPD, BPDYB and TPDYB pyridine molecules were all able to form a stable two-component co-assembled structure with the H5BHB molecule, and in these co-assembled structures, the H5BHB molecule still takes the form of a dimer. It was found that the pyridine molecules were able to regulate the self-assembly structure of the H5BHB molecule, and the molecular arrangement of the co-assembly structures varies with the shape of the pyridine molecules. Based on the analysis of the STM results and density functional theory (DFT) calculations, the formation mechanism of the assembled structures was revealed.

Dynamics of Hepatitis B Virus Capsid Protein Dimer Regulate Assembly through an Allosteric Network.

While there is an effective vaccine for Human Hepatitis B Virus (HBV), 257 million people have chronic infections for which there is no cure. The assembly process for the viral capsid is a potential therapeutic target. In order to understand the capsid assembly process, we investigated the dimeric building blocks of the capsid. To understand what blocks assembly, we took advantage of an assembly incompetent mutant dimer, Cp149-Y132A, located in the interdimer interface. This mutation leads to changes in protein dynamics throughout the structure of the dimer as measured by hydrogen-deuterium exchange mass spectrometry (HDX-MS). To further understand how the HBV capsid assembles, the homologue woodchuck HBV (WHV) capsid protein dimer (Cp) was used. WHV is more stable than HBV in HDX-MS and native mass spectrometry experiments. Because the WHV Cp assembles more rapidly into viral capsids than HBV, it was suspected that an increase in stability of the intradimer interface and/or in the contact region leads to increased assembly rates. The differences in dynamics when comparing HBV and human Cp149-Y132A as well as the differences in dynamics when comparing the HBV and WHV Cps allowed us to map an allosteric network within the HBV dimer. Through a careful comparison of structure, stability, and dynamics using four different capsid protein dimers, we conclude that protein subunit dynamics regulate HBV capsid assembly.

Cryo-EM structures of S-OPA1 reveal its interactions with membrane and changes upon nucleotide binding.

Mammalian mitochondrial inner membrane fusion is mediated by optic atrophy 1 (OPA1). Under physiological conditions, OPA1 undergoes proteolytic processing to form a membrane-anchored long isoform (L-OPA1) and a soluble short isoform (S-OPA1). A combination of L-OPA1 and S-OPA1 is essential for efficient membrane fusion; however, the relevant mechanism is not well understood. In this study, we investigate the cryo-electron microscopic structures of S-OPA1-coated liposomes in nucleotide-free and GTPγS-bound states. S-OPA1 exhibits a general dynamin-like structure and can assemble onto membranes in a helical array with a dimer building block. We reveal that hydrophobic residues in its extended membrane-binding domain are critical for its tubulation activity. The binding of GTPγS triggers a conformational change and results in a rearrangement of the helical lattice and tube expansion similar to that of S-Mgm1. These observations indicate that S-OPA1 adopts a dynamin-like power stroke membrane remodeling mechanism during mitochondrial inner membrane fusion.

A Supramolecular Strategy toward an Efficient and Selective Capture of Platinum(II) Complexes.

Recovering heavy and precious metals from wastewater is both economically and environmentally attractive. However, a challenge still remains in how to realize the highly selective removal and recovery of a particular metal of interest, such as platinum. Here we experimentally demonstrate a two-dimensional (2D) supramolecular polymer that can serve as a host for the highly selective capture of anionic platinum(II) (PtII) species including its metal-organic complexes and water-soluble ions. This host polymer possesses a 2D honeycomb-like nanostructure noncovalently bridged by cationic alkynylplatinum(II) terpyridine dimers. Anionic PtII guests readily bind to the dimeric PtII building blocks of the internal cavities via electrostatic and specific PtII···PtII interactions. Such unique host-guest interactions have endowed thin membranes comprising highly oriented supramolecular polymers with a versatile ability to selectively recognize and adsorb anionic PtII species over other metal ions in water upon simple filtration.

Mechanistically Driven Control over Cubane Oxo Cluster Catalysts.

Predictive and mechanistically driven access to polynuclear oxo clusters and related materials remains a grand challenge of inorganic chemistry. We here introduce a novel strategy for synthetic control over highly sought-after transition metal {M4O4} cubanes. They attract interest as molecular water oxidation catalysts that combine features of both heterogeneous oxide catalysts and nature's cuboidal {CaMn4O5} center of photosystem II. For the first time, we demonstrate the outstanding structure-directing effect of straightforward inorganic counteranions in solution on the self-assembly of oxo clusters. We introduce a selective counteranion toolbox for the controlled assembly of di(2-pyridyl) ketone (dpk) with M(OAc)2 (M = Co, Ni) precursors into different cubane types. Perchlorate anions provide selective access to type 2 cubanes with the characteristic {H2O-M2(OR)2-OH2} edge-site, such as [Co4(dpy-C{OH}O)4(OAc)2(H2O)2](ClO4)2. Type 1 cubanes with separated polar faces [Co4(dpy-C{OH}O)4(L2)4] n+ (L2 = OAc, Cl, or OAc and H2O) can be tuned with a wide range of other counteranions. The combination of these counteranion sets with Ni(OAc)2 as precursor selectively produces type 2 Co/Ni-mixed or {Ni4O4} cubanes. Systematic mechanistic experiments in combination with computational studies provide strong evidence for type 2 cubane formation through reaction of the key dimeric building block [M2(dpy-C{OH}O)2(H2O)4]2+ with monomers, such as [Co(dpy-C{OH}O)(OAc)(H2O)3]. Furthermore, both experiments and DFT calculations support an energetically favorable type 1 cubane formation pathway via direct head-to-head combination of two [Co2(dpy-C{OH}O)2(OAc)2(H2O)2] dimers. Finally, the visible-light-driven water oxidation activity of type 1 and 2 cubanes with tuned ligand environments was assessed. We pave the way to efficient design concepts in coordination chemistry through ionic control over cluster assembly pathways. Our comprehensive strategy demonstrates how retrosynthetic analyses can be implemented with readily available assembly directing counteranions to provide rapid access to tuned molecular materials.

Synthesis, structure, spectral characteristic and photocatalytic degradation of organic dyes of a copper metal-organic framework based on tri(triazole) and pimelate

A copper(II) metal-organic framework {[Cu(ttpa)(pim)]·H2O}n (1) was synthesized and characterized by EA, IR, X-ray powder diffraction, optical band gaps, VB XPS spectra and luminescence (ttpa = tris(4-(1,2,4-triazol-1-yl)phenyl)amine, pim = pimelate). 1 exhibits the 3D pcu topology containing the [Cu2(COO)4] dimer building block. Eg, Ev and Ec of 1 were 2.37, 1.64 and -0.73 eV, respectively. MOF 1 exhibits a highly photocatalytic efficiency for the degradation of methylene blue and rhodamine B by visible light irradiation. The photocatalyst 1 is very stable after photocatalytic experiment and can be reused for at least five times. The photocatalytic mechanism was detailedly assumed and confirmed by the photocatalytic reaction in the presence of the hydroxyl radical scavenger mannitol and trapping agent 1,4-benzenedicarbolic acid.

Studies on acid stability and solid-phase block synthesis of peptide-peptoid hybrids: ligands for formyl peptide receptors.

α-Peptoids as well as peptide/α-peptoid hybrids and peptide/β-peptoid hybrids constitute major classes of proteolytically stable peptidomimetics that have been extensively investigated as mimetics of biologically active peptides. Representatives of lipidated peptide/β-peptoid hybrids have been identified as promising immunomodulatory lead compounds, and hence access to these via protocols suitable for gram-scale synthesis is warranted to enable animal in vivo studies. Recent observations indicated that several byproducts appear in crude mixtures of relatively short benzyl-based peptide/β-peptoid oligomers, and that these were most predominant when the β-peptoid units displayed an α-chiral benzyl side chain. This prompted an investigation of their stability under acidic conditions. Simultaneous deprotection and cleavage of peptidomimetics containing either α-chiral α- or β-peptoid residues required treatment with strong acid only for a short time to minimize the formation of partially debenzylated byproducts. The initial work on peptide/β-peptoid oligomers with an alternating design established that it was beneficial to form the amide bond between the carboxyl group of the α-amino acid and the congested amino functionality of the β-peptoid residue in solution. To further simplify oligomer assembly on solid phase, we now present a protocol for purification-free solid-phase synthesis of tetramericbuilding blocks. Next, syntheses of peptidomimetic ligands via manual solid-phase methodologies involving tetramericbuilding blocks were found to give more readily purified products as compared to those obtained with dimericbuilding blocks. Moreover, the tetramericbuilding blocks could be utilized in automated synthesis with microwave-assisted heating, albeit the purity of the crude products was not increased.

Assembly of Two Metal-Organic Frameworks Based on Distinct Cobalt Dimeric Building Blocks Induced by Ligand Modification: Gas Adsorption and Magnetic Properties.

Solvothermal reaction of 3,5-di(pyridin-4-yl) benzoic acid (HDPB) with Co(II) leads to a novel metal-organic framework, [Co2O(DPB)2(DMF)2]· xS (1), which represents a rare reo-type net with trigonal prismatic cobalt dimer, [Co2O(CO2)2N4], as building blocks to construct a 3D framework containing three different types of nanoscale M12L12 and M24L12 polyhedron cages. More interestingly, under the same condition, the assembly of 4-methyl-3,5-di(pyridin-4-yl) benzoic acid (HMDPB) with Co(II) facilitates the formation of a cationic framework, [Co2(MDPB)3(DMF)](NO3)· xS (2), with cobalt dimer, [Co2(CO2)3N4], as building blocks. Complex 2 represents the first example of a zeolite-like network with 48-nuclear SOD cage. The significant effect of subtle modification of ligand on the overall MOFs is discussed. Moreover, the gas adsorption studies reveal that 1 exhibits permanent porosity and selective CO2 uptake. Variable-temperature magnetic susceptibility measurements show that both 1 and 2 exhibit antiferromagnetic behavior.

Developing High Field MRI Contrast Agents by Tuning the Rotational Dynamics: Bisaqua GdAAZTA‐based Dendrimers

AbstractMonomeric and dimeric AAZTA‐based bifunctional chelators (AAZTA=6‐amino‐6‐methylperhydro‐1,4‐diazepine tetraacetic acid) were attached to different generations (G0, G1 and G2) of ethylenediamine‐cored PAMAM dendrimers (PAMAM=polyamidoamine) to obtain a series of six dendrimeric systems with 4 to 32 chelates at the periphery. These GdIII‐loaded dendrimers have molecular weight ranging from 3.5 to 25 kDa, thus allowing a systematic investigation on the changes in relaxivity (r1) with the variation of the rotational dynamics following the increase in molecular size. Variable‐temperature 17O NMR (on the dimeric building block Gd2L2) and 1H Nuclear Magnetic Relaxation Dispersion measurements at different temperatures indicate that the water exchange lifetime (τM∼90 ns) of the two inner sphere water molecules does not represent a limiting factor to the relaxivity of the systems. The r1 values at 1.5 T (60 MHz) and 298 K increases from 10.2 mM−1 s−1 for the monomer GdL1 to 31.4 mM−1 s−1 for the dendrimer Gd32G2‐32 (+308 %). However, the relaxivity (per Gd) does not show a linear dependence on the molecular mass, but rather the enhancement tends to attenuate markedly for larger systems. This effect has been attributed to the growing decrease in correlation between local rotational motions and global molecular tumbling.

Specific sequences in the N-terminal domain of human small heat-shock protein HSPB6 dictate preferential hetero-oligomerization with the orthologue HSPB1

Small heat-shock proteins (sHSPs) are a conserved group of molecular chaperones with important roles in cellular proteostasis. Although sHSPs are characterized by their small monomeric weight, they typically assemble into large polydisperse oligomers that vary in both size and shape but are principally composed of dimeric building blocks. These assemblies can include different sHSP orthologues, creating additional complexity that may affect chaperone activity. However, the structural and functional properties of such hetero-oligomers are poorly understood. We became interested in hetero-oligomer formation between human heat-shock protein family B (small) member 1 (HSPB1) and HSPB6, which are both highly expressed in skeletal muscle. When mixed in vitro, these two sHSPs form a polydisperse oligomer array composed solely of heterodimers, suggesting preferential association that is determined at the monomer level. Previously, we have shown that the sHSP N-terminal domains (NTDs), which have a high degree of intrinsic disorder, are essential for the biased formation. Here we employed iterative deletion mapping to elucidate how the NTD of HSPB6 influences its preferential association with HSPB1 and show that this region has multiple roles in this process. First, the highly conserved motif RLFDQXFG is necessary for subunit exchange among oligomers. Second, a site ∼20 residues downstream of this motif determines the size of the resultant hetero-oligomers. Third, a region unique to HSPB6 dictates the preferential formation of heterodimers. In conclusion, the disordered NTD of HSPB6 helps regulate the size and stability of hetero-oligomeric complexes, indicating that terminal sHSP regions define the assembly properties of these proteins.

Weak hydrogen bonding and fluorous interactions in the chloride and bromide salts of 4-[(2,2,3,3-tetrafluoropropoxy)methyl]pyridinium.

Neutralization of 4-[(2,2,3,3-tetrafluoropropoxy)methyl]pyridine with hydrohalo acids HX (X = Cl and Br) yielded the pyridinium salts 4-[(2,2,3,3-tetrafluoropropoxy)methyl]pyridinium chloride, C9H10F4NO+·Cl-, (1), and 4-[(2,2,3,3-tetrafluoropropoxy)methyl]pyridinium bromide, C9H10F4NO+·Br-, (2), both carrying a fluorous side chain at the para position of the pyridinium ring. Single-crystal X-ray diffraction techniques revealed that (1) and (2) are isomorphous. The halide anions accept four hydrogen bonds from N-H, ortho-C-H and CF2-H groups. Two cations and two anions form a centrosymmetric dimeric building block, utilizing complimentary N-H...X...H-Csp3 connections. These dimers are further crosslinked, utilizing another complimentary Csp2-H...X...H-Csp2 connection. The pyridinium rings are π-stacked, forming columns running parallel to the a axis that make angles of ca 44-45° with the normal to the pyridinium plane. There are also supramolecular C-H...F-C interactions, namely bifurcated C-H...F and bifurcated C-F...H interactions; additionally, one type II C-F...F-C halogen bond has been observed.