Bioprospecting the Antibiofilm and Antimicrobial Activity of Soil and Insect Gut Bacteria

Antimicrobial resistance is a growing concern in public health and current research shows an important role for bacterial biofilms in recurrent or chronic infections. New strategies, therefore, are necessary to overcome antimicrobial resistance, through the development of new therapies that could alter or inhibit biofilm formation. In this sense, antibiofilm natural products are very promising. In this work, a bioprospection of antimicrobial and antibiofilm extracts from Uruguayan soil bacteria and insect gut bacteria was carried out. Extracts from extracellular broths were tested for their ability to inhibit planktonic cell growth and biofilm formation. Genomic analysis of Bacillus cereus ILBB55 was carried out. All extracts were able to inhibit the growth of, at least, one microorganism and several extracts showed MICs lower than 500 µg mL⁻¹ against microorganisms of clinical relevance (Staphylococcus aureus, Pseudomonas aeruginosa, and Enterobacter cloacae). Among the extracts evaluated for biofilm inhibition only ILBB55, from B. cereus, was able to inhibit, S. aureus (99%) and P. aeruginosa (62%) biofilms. Genomic analysis of this strain showed gene clusters similar to other clusters that code for known antimicrobial compounds. Our study revealed that extracts from soil bacteria and insect gut bacteria, especially from B. cereus ILBB55, could be potential candidates for drug discovery to treat infectious diseases and inhibit S. aureus and P. aeruginosa biofilms.     

Explored routes to unknown polyfluoroorganyliodine hexafluorides, RFIF6

Two routes to R_FIF₆ compounds were investigated: (a) the substitution of F by R_F in IF₇ and (b) the fluorine addition to iodine in R_FIF₄ precursors. For route (a) the reagents C₆F₅SiMe₃, C₆F₅SiF₃, [NMe₄][C₆F₅SiF₄], C₆F₅BF₂, and 1,4-C₆F₄(BF₂)₂ were tested. C₆F₅IF₄ and CF₃CH₂IF₄ were used in route (b) and treated with the fluoro-oxidizers IF₇, [O₂][SbF₆]/KF, and K₂[NiF₆]/KF. The observed sidestep reactions in case of routes (a) and (b) are discussed. Interaction of C₆F₅SiX₃ (X = Me, F), C₆F₅BF₂, 1,4-C₆F₄(BF₂)₂ with IF₇ gave exclusively the corresponding ring fluorination products, perfluorinated cyclohexadiene and cyclohexene derivatives, whereas [NMe₄][C₆F₅SiF₄] and IF₇ formed mixtures of C₆F_nIF₄ and C₆F_nH compounds (n = 7 and 9). CF₃CH₂IF₄ was not reactive towards the fluoro-oxidizer IF₇, whereas C₆F₅IF₄ formed C₆F_nIF₄ compounds (n = 7 and 9). C₆F₅IF₄ and CF₃CH₂IF₄ were inert towards [O₂][SbF₆] in anhydrous HF. CF₃CH₂IF₄ underwent C-H fluorination and C-I bond cleavage when treated with K₂[NiF₆]/KF in HF. The fluorine addition property of IF₇ was independently demonstrated in case of perfluorohexenes. C₄F₉CFCF₂ and IF₇ underwent oxidative fluorine addition at −30 °C, and the isomers (CF₃)₂CFCFCFCF₃ (cis and trans) formed very slowly perfluoroisohexanes even at 25 °C. The compatibility of IF₇ and selected organic solvents was investigated. The polyfluoroalkanes CF₃CH₂CHF₂ (PFP), CF₃CH₂CF₂CH₃ (PFB), and C₄F₉Br are inert towards iodine heptafluoride at 25 °C while CF₃CH₂Br was slowly converted to CF₃CH₂F. Especially PFP and PFB are new suitable organic solvents for IF₇.     

New reactor for production of tungsten disulfide hollow onion-like (inorganic fullerene-like) nanoparticles

MS₂ (M=Mo, W) hollow onion-like nanoparticles were the first inorganic fullerene-like (IF) materials, found in 1992. Understanding of the IF-MS₂ growth mechanism in 1996 enabled us to build a rather simple reactor, which produced about 0.4 g per batch, of an almost pure IF-WS₂ powder. Soon after, it was found that the new powder showed better tribological properties compared with the regular MS₂ (M=Mo, W) powder, which is a well-known solid lubricant. The present work shows a new synthetic approach, which allows for a scale-up of IF-WS₂ production by more than two orders of magnitude. The falling-bed and, especially, fluidized-bed methods, which are presented here, pave the way for an almost ideal growth condition of the IF synthesis from an oxide precursor. As a result, the presently produced IF has a more uniform (spherical) shape and can grow to a larger size (up to 0.5 μm). It is expected that the relatively spherical IF-WS₂ nanoparticles, which are produced by the falling (fluidized) bed reactor, will exhibit superior tribological properties, than reported before.     

Activity and Diversity of Microorganisms in Root Zone of Plant Species Spontaneously Inhabiting Smelter Waste Piles

The aim was to assess plant driven changes in the activity and diversity of microorganisms in the top layer of the zinc and lead smelter waste piles. The study sites comprised two types (flotation waste—FW and slag waste—SW) of smelter waste deposits in Piekary Slaskie, Poland. Cadmium, zinc, lead, and arsenic contents in these technosols were extremely high. The root zone of 8 spontaneous plant species (FW—Thymus serpyllum, Silene vulgaris, Solidago virgaurea, Echium vulgare, and Rumex acetosa; and SW—Verbascum thapsus; Solidago gigantea, Eupatorium cannabinum) and barren areas of each waste deposit were sampled. We observed a significant difference in microbial characteristics attributed to different plant species. The enzymatic activity was mostly driven by plant-microbial interactions and it was significantly greater in soil affected by plants than in bulk soil. Furthermore, as it was revealed by BIOLOG Ecoplate analysis, microorganisms inhabiting barren areas of the waste piles rely on significantly different sources of carbon than those found in the zone affected by spontaneous plants. Among phyla, Actinobacteriota were the most abundant, contributing to at least 25% of the total abundance. Bacteria belonging to Blastococcus genera were the most abundant with the substantial contribution of Nocardioides and Pseudonocardia, especially in the root zone. The contribution of unclassified bacteria was high—up to 38% of the total abundance. This demonstrates the unique character of bacterial communities in the smelter waste.     

An Exploration of Seaweed Polysaccharides Stimulating Denitrifying Bacteria for Safer Nitrate Removal

Excessive use of nitrogen fertilizer in intensively managed agriculture has resulted in abundant accumulation of nitrate in soil, which limits agriculture sustainability. How to reduce nitrate content is the key to alleviate secondary soil salinization. However, the microorganisms used in soil remediation cause some problems such as weak efficiency and short survival time. In this study, seaweed polysaccharides were used as stimulant to promote the rapid growth and safer nitrate removal of denitrifying bacteria. Firstly, the growth rate and NO₃⁻-N removal capacity of three kinds of denitrifying bacteria, Bacillus subtilis (BS), Pseudomonas stutzeri (PS) and Pseudomonas putida (PP), were compared. The results showed that Bacillus subtilis (BS) had a faster growth rate and stronger nitrate removal ability. We then studied the effects of Enteromorpha linza polysaccharides (EP), carrageenan (CA), and sodium alginate (AL) on growth and denitrification performance of Bacillus subtilis (BS). The results showed that seaweed polysaccharides obviously promoted the growth of Bacillus subtilis (BS), and accelerated the reduction of NO₃⁻-N. More importantly, the increased NH₄⁺-N content could avoid excessive loss of nitrogen, and less NO₂⁻-N accumulation could avoid toxic effects on plants. This new strategy of using denitrifying bacteria for safely remediating secondary soil salinization has a great significance.     

土壤铜污染的微生物及酶学指标研究

通过室内培养试验,研究了土壤铜污染对土壤微生物基础呼吸及土壤脲酶、脱氢酶、酸性磷酸酶的影响。结果表明,土壤微生物基础呼吸在低水平铜（≤100mg／kg）添加下呈现出先上升后下降的趋势,而随着土壤铜添加水平的进一步提高（〉100mg／kg）,微生物基础呼吸作用迅速增强;土壤脲酶则随着铜含量的增加呈现出不断下降趋势,土壤磷酸酶活性则在低水平下上升而随着添加水平的进一步提高迅速降低。可见,这两种酶对土壤铜毒害反应灵敏,可作为土壤铜污染评价的指标;而土壤脱氢酶则对铜含量的变化没有表现出明显的统计规律性,不适宜作为土壤铜污染评价的酶学指标。     

A first methodical approach to salts with unsymmetrical fluorophenyl(pentafluorophenyl)difluoroiodonium(V) cations [Rf(RF)IF2] (Rf=x-FC6H4, x=2, 3, 4; RF=C6F5)

A promising approach to the unknown type of [Ar′(Ar)IF₂]X salts is offered. x-FC₆H₄IF₄ (x=2, 3, 4) reacts with C₆F₅BF₂ in CH₂Cl₂ and forms [x-FC₆H₄(C₆F₅)IF₂][BF₄] salts in good yields. For [4-FC₆H₄(C₆F₅)IF₂][BF₄] the fluoro-oxidizer property is shown in reactions with weakly reducing agents like E(C₆F₅)₃ (E=P, As, Sb, Bi) and ArI (Ar=4-FC₆H₄, C₆F₅). The fluorine/aryl substitution method is also applied to the synthesis of [(4-FC₆H₄)₂IF₂][BF₄], an example with two identical aryl groups in the difluoroiodonium(V) moiety.     

Pentafluorphenyliod(V)-Verbindungen. 2. Pentafluorphenyliodtetrafluorid C6F5IF4: Synthese durch Fluor-Aryl-Substitution an IF5 — Eigenschaften und Struktur. Strukturanalyse der monovalenten Iodstammverbindung C6F5I

Pentafluorophenyliodine(V) Compounds. 2. Pentafluorophenyliodine Tetrafluoride C₆F₅IF₄: Synthesis via Fluorine-Aryl-Substitution on IF₅ — Properties and Structure. Structural Analysis of the Monovalent Iodine Parent Compound C₆F₅I The nucleophilic fluorine-aryl substitution reaction on IF₅ with pentafluorophenyl, Bi(C₆F₅)₃, leads to C₆F₅IF₄ in good yields and high purity. The thermal stability of C₆F₅IF₄ and its NMR spectrometric behaviour in solution will be described. The crystal structure of C₆F₅IF₄ will be discussed in comparison to IF₅. In addition data of the molecular and crystal structure of the monovalent iodine parent compound C₆F₅I will be given.     

Biodegradability of bio-flour filled biodegradable poly(butylene succinate) bio-composites in natural and compost soil

This study investigated the biodegradability of PBS and bio-flour, which is a poly(butylene succinate) (PBS) bio-composite filled with rice-husk flour (RHF) reinforcing, in natural and aerobic compost soil. The percentage weight loss and the reduction in mechanical properties of PBS and the bio-composites in the compost soil burial test were significantly greater than those in the natural soil burial test. These results were supported by degraded surface of PBS and bio-composites observed through morphological study and the total colony count of natural soil was lower than that of compost soil. The biodegradability of the bio-composites was enhanced with increasing bio-flour content because the bio-flour is easily attacked by microorganisms. As the biodegradability test progressed over time up to 80 days, the molecular weight of PBS decreased in the soil burial test. We confirmed by attenuated total reflectance (FTIR-ATR) analyser that the chemical structures of PBS and the bio-composites were changed after the compost burial test. The glass transition temperature (T_g), melting temperature (T_m), crystallization temperature (T_c), heat of fusion (ΔH_f) and heat of crystallization (ΔH_c) of the natural and composted soil tested PBS were investigated using differential scanning calorimetry (DSC). From the results, we concluded that use of these bio-composites will reduce the environmental problems associated with waste pollution and the study findings support the predicted application of bio-composites as “green-composites” or “eco-materials”.     

Phenyliodine(V) fluorides

The known compound phenyltetrafluoroiodine(V) is shown by X-ray diffraction to have a tetragonal pyramidal structure with an apical phenyl group. This structure is compared to that of IF(OTeF₅)₄, where the apical position is occupied by the fluorine atom. C₆H₅IF₄ adds F⁻, forming C₆H₅IF₅⁻, which has a pentagonal pyramidal structure with an apical phenyl group. Fluoride abstraction from C₆H₅IF₄ by SbF₅ results in the formation of the cation C₆H₅IF₃⁺, which has a pseudotrigonal bipyramidal structure with the phenyl group occupying an equatorial position. Isoelectronic C₆H₅IOF₂ has a similar structure, with the phenyl group and oxygen atom both occupying equatorial positions.     

Porphyrin–Schiff Base Conjugates Bearing Basic Amino Groups as Antimicrobial Phototherapeutic Agents

New porphyrin–Schiff base conjugates bearing one (6) and two (7) basic amino groups were synthesized by condensation between tetrapyrrolic macrocycle-containing amine functions and 4-(3-(N,N-dimethylamino)propoxy)benzaldehyde. This approach allowed us to easily obtain porphyrins substituted by positive charge precursor groups in aqueous media. These compounds showed the typical Soret and four Q absorption bands with red fluorescence emission (Φ_F ~ 0.12) in N,N-dimethylformamide. Porphyrins 6 and 7 photosensitized the generation of O₂(¹Δ_g) (Φ_Δ ~ 0.44) and the photo-oxidation of L-tryptophan. The decomposition of this amino acid was mainly mediated by a type II photoprocess. Moreover, the addition of KI strongly quenched the photodynamic action through a reaction with O₂(¹Δ_g) to produce iodine. The photodynamic inactivation capacity induced by porphyrins 6 and 7 was evaluated in Staphylococcus aureus, Escherichia coli, and Candida albicans. Furthermore, the photoinactivation of these microorganisms was improved using potentiation with iodide anions. These porphyrins containing basic aliphatic amino groups can be protonated in biological systems, which provides an amphiphilic character to the tetrapyrrolic macrocycle. This effect allows one to increase the interaction with the cell wall, thus improving photocytotoxic activity against microorganisms.     

Chitinase Chit62J4 Essential for Chitin Processing by Human Microbiome Bacterium Clostridium paraputrificum J4

Commensal bacterium Clostridium paraputrificum J4 produces several extracellular chitinolytic enzymes including a 62 kDa chitinase Chit62J4 active toward 4-nitrophenyl N,N′-diacetyl-β-d-chitobioside (pNGG). We characterized the crude enzyme from bacterial culture fluid, recombinant enzyme rChit62J4, and its catalytic domain rChit62J4cat. This major chitinase, securing nutrition of the bacterium in the human intestinal tract when supplied with chitin, has a pH optimum of 5.5 and processes pNGG with K_m = 0.24 mM and k_cat = 30.0 s⁻¹. Sequence comparison of the amino acid sequence of Chit62J4, determined during bacterial genome sequencing, characterizes the enzyme as a family 18 glycosyl hydrolase with a four-domain structure. The catalytic domain has the typical TIM barrel structure and the accessory domains—2x Fn3/Big3 and a carbohydrate binding module—that likely supports enzyme activity on chitin fibers. The catalytic domain is highly homologous to a single-domain chitinase of Bacillus cereus NCTU2. However, the catalytic profiles significantly differ between the two enzymes despite almost identical catalytic sites. The shift of pI and pH optimum of the commensal enzyme toward acidic values compared to the soil bacterium is the likely environmental adaptation that provides C. paraputrificum J4 a competitive advantage over other commensal bacteria.     

Secondary Metabolites from Hericium erinaceus and Their Anti-Inflammatory Activities

Hericium erinaceus, a culinary and medicinal mushroom, is widely consumed in Asian countries. Chemical investigation on the fruiting bodies of Hericium erinaceus led to the isolation of one new ergostane-type sterol fatty acid ester, erinarol K (1); and eleven known compounds: 5α,8α -epidioxyergosta-6,22-dien-3β-yl linoleate (2); ethyl linoleate (3); linoleic acid (4); hericene A (5); hericene D (6); hericene E (7); ergosta-4,6,8(14),22-tetraen-3-one (8); hericenone F (9); ergosterol (10); ergosterol peroxide (11); 3β,5α,6α,22E-ergosta-7,22-diene-3,5,6-triol 6-oleate (12). The chemical structures of the compounds were determined by 1D and 2D NMR (nuclear magnetic resonance) spectroscopy, mass spectra, etc. Anti-inflammatory effects of the isolated aromatic compounds (5–7, 9) were evaluated in terms of inhibition of pro-inflammatory mediator (TNF-α, IL-6 and NO) production in lipopolysaccharide (LPS)-stimulated murine RAW 264.7 macrophage cells. The results showed that compounds 5 and 9 exhibited moderate activity against TNF-α (IC₅₀: 78.50 μM and 62.46 μM), IL-6 (IC₅₀: 56.33 μM and 48.50 μM) and NO (IC₅₀: 87.31 μM and 76.16 μM) secretion. These results supply new information about the secondary metabolites of Hericium erinaceus and their anti-inflammatory effects.     

Intercalation of halogen fluorides into graphite

IF₇ intercalates into graphite accompanied by the partial fluorination of the graphite host. The intercalated species was identified as IF₅ by IR and ¹⁹F nmr spectroscopies. Mass spectrometric analyses of the gases evolved from the intercalate showed only IF₅ and fluorocarbons. Iodine pentafluoride intercalates only in the presence of HF, yielding a compound with the stoichiometry C₈IF₅ and no fluorination of the graphite host. Careful elimination of even traces of HF resulted in no intercalation. Evolved gas analysis showed that the only species recovered from the intercalation was IF₅. The remaining interhalogens, ClF₅, ClF₃, BrF₅ and BrF₃ all intercalate into graphite with extensive fluorination of the lattice. In the case of these four compounds, the intercalate proved to be more difficult to characterize, e.g. stoichiometry was often variable, and ¹⁹F nmr yielded resonances that did not agree with any known halogen fluorides. Thermal decomposition of these intercalates showed little or no gas evolution until relatively high temperatures were reached, whereupon Cl₂ or Br₂ was evolved, followed by fluorocarbons.     

Die NMR-Spektren von CF3I,CF3IF2 und CF3IF4

The NMR Spectra of CF₃I, CF₃IF₂, and CF₃IF₄ The ¹⁹F-NMR and ¹³C-NMR spectra of CF₃I, CF₃IF₂ and CF₃IF₄ were recorded in acetonitrile solution. The chemical shifts of the CF₃-groups are strongly dependent on the oxidation state of the iodine atom. With increasing oxidation state the resonances of the CF₃-groups in the ¹⁹F-NMR spectra are characteristically shifted to high field, whereas in the ¹³C-NMR spectra a characteristic shift to low field is measured. The absolute value of the coupling constants ¹J(¹⁹F? ¹³C) increases with increasing oxidation state from 344 Hz (CF₃I) via 354 Hz (CF₃IF₂) to 359 Hz (CF₃IF₄).     

Tutorial review: Bohr circular orbit diagrams for some fluorine-containing molecules

Examples are provided of Bohr circular orbit diagrams to represent the electronic structures of some fluorine-containing molecules. The orbit diagrams are constructed from a 2n × n factorisation of the atomic shell-structure formula 2n², with n = 1, 2, 3, … Particular attention is given to orbit diagrams and the associated valence bond structures for the hypercoordinate molecules and ions PF₅ and NF₅, F₃⁻ and XeF₂, IF₅ and XeF₅⁺, XeF₅⁻, IF₈⁻, XeF₈²⁻, ReF₈⁻ and TaF₈³⁻, ZrF₈⁴⁻, ZrF₇³⁻, Re₂F₈²⁻, and high-spin CoF₆³⁻.Aspects of the electronic structures of D_3h-symmetry PF₅ and NF₅ are contrasted via the use of orbital valence bond considerations, and the results of STO-3G valence bond calculations are reported for these species.     

The formation of oxygen-containing perfluorocyclohexadien-1-yliodine tetrafluorides

The electrophilic oxygenation of pentafluorophenyl iodo compounds C₆F₅IF_n with iodine in different valencies (n = 0, 2, 4) using XeF₂-H₂O in HF allowed access to new organoiodine(V) compounds, namely isomeric oxopentafluorocyclohexadien-1-yliodine tetrafluorides, C₆(O)F₅IF₄.     

Substitution reactions of IF5

Using silyl protected organic hydroxo compounds substitution of fluorine in IF₅ is successful.Reacting IF₅ with Si(OCH₃)₄ in CH₃CN or SO₂ using different molar ratios it was shown that in the series IF_5?n(OCH₃)_n only the first member IF₄(OCH₃) (n=1) is stable enough to be isolated. The product in solution with n=2 bismutates to products with n=1 and n=3 if isolated as solids. The last one decomposes to the new oxo compound IF₂O(OCH₃) under elimination of CH₃OCH₃. With n=4,5 only redox reaction products could be isolated.IF₂O(OCH₃) can also be obtained by treating IF₄(OCH₃) with (CH₃)₆Si₂O. Similarly reaction of IF₅ with the disiloxane represents a new method to win IOF₃. Excess of the oxygen transfer reagent leads to formation of IO₂F and I₂O₅. An other oxo compound, IO(CH₃COO)₃, can be prepared by disolving IF₅, IOF₃ or IO₂F in acetic acid anhydride.Reactions of IF₅ with trimethylsilyl protected fluorinated benzoic acids R_fCOOSi(CH₃)₃ (R_f = C₆F₅, 4HC₆F₄) appeared to be independent of the educts molar ratios because the only products are IF(R_fCOO)₄.In order to stabilize iodine (V) derivates with bifunctional chelating oxo ligands we applicated bis(trimethylsilyl) pinacolate, and in smooth reactions we yielded IF₃[OC(CH₃)₂C(CH₃)₂O] and IF[OC(CH₃)₂  C(CH₃)₂O]₂, in which iodine is part of five membered heterocyclic rings. The ¹⁹F-nmr-spectra are consistent with the diolate occupying the axiale and equatorial positions.An extension of the silyl method is the new synthesis of C₆F₅IF₄ which could be obtained in the smooth reaction of IF₅ with stochiometric amounts of Si(C₆F₅)₄.     

Effects of 17α-ethinylestradiol on zoo- and phytoplankton in lentic microcosms

The effects of 17-ethinylestradiol (EE), an endocrine disruptor, on zoo- and phytoplankton were studied in outdoor 230-L still-water microcosms. Cell density and biomass, diversity, and community composition were analyzed. Five microcosms were treated by controlled release for six weeks, three by direct application of EE. To investigate recovery, sampling was continued for four weeks after treatment. Most characteristics of the zooplankton were not unambiguously affected by EE. Only the relative density of copepods, especially of their larvae, decreased significantly after EE application. For phytoplankton, no unambiguous concentration- or toxodose-correlated effects on any biotic characteristics could be found. However, most properties of the phytoplankton deviated from those of controls, i.e. tended to be smaller (number of species per microcosm, biomass, cell density) or covered a wider range (diversity, evenness). PCA indicated a shift of species structure in the treated microcosms. This was supported by the species scores calculated by the principal response curve method, although the principal response curve itself showed no clear EE-correlated shifts. High variability within the biocenosis between microcosms and over time, probably because of disturbance of the ecosystem before starting of the test, might have superimposed EE-dependent effects.Abbreviations c _dt Canonical coefficient - CRD Controlled-release device - E Shannon–Wiener index for evenness - EC10 Effect concentration for 10% of maximum effect - EC50 Effect concentration for 50% of maximum effect - EE 17-Ethinylestradiol - H Shannon–Wiener index for diversity - LPDE Low density polyethylene - NOEC No observed effect concentration - PCA Principal component analysis - PRC Principal response curve - RDA Redundancy analysis - SD Standard deviation     

Preparation of polyfluorinated cycloalk-1-enyl-, alk-1-enyl-, and alkyliodine tetrafluorides using XeF2 in the presence of appropriate Lewis acids as fluorooxidant

Previously unknown polyfluorocyclohexenyl, and acyclic perfluoroalkenyliodine tetrafluorides were prepared in high yields. Perfluorocyclohex-1-enyliodine tetrafluoride was obtained from pentafluoroiodobenzene using XeF₂-NbF₅ in aHF. The reaction of C₆F₅I with the weaker fluorooxidant XeF₂-BF₃ in 1,1,1,3,3-pentafluorobutane (PFB) yielded C₆F₅IF₂, perfluorocyclohexa-1,4-dienyliodine difluoride, C₆F₅IF₄, perfluorocyclohexa-1,4, and 1,3-dienyliodine tetrafluoride as intermediate products on parallel reaction routes. Both perfluoroalkenyl iodides, cis- and trans-(CF₃)₂CFCFCFI, reacted with XeF₂-BF₃ in PFB to give the corresponding perfluoroalkenyliodine tetrafluorides, cis- and trans-(CF₃)₂CFCFCFIF₄. Even perfluoroalkyl iodides can be fluorinated by this reagent as was demonstrated by the preparation of C₆F₁₃IF₄ from C₆F₁₃I. Generally, the CFCIF_n fragment (n = 0, 2, or 4) in cyclic or acyclic perfluoroalkenyliodine compounds R_FIF_n did not undergo a transformation to the corresponding perfluoroalkyliodine compound. Furthermore, no perfluoroorganoiodine hexafluorides were detected in reactions with the fluorooxidant XeF₂-aHF or BF₃ or NbF₅.