Hydroxyl Unit Research Articles

Site-Selective C-O Bond Editing of Unprotected Saccharides.

Glucose and its polyhydroxy saccharide analogs are complex molecules that serve as essential structural components in biomacromolecules, natural products, medicines, and agrochemicals. Within the expansive realm of saccharides, a significant area of research revolves around chemically transforming naturally abundant saccharide units to intricate or uncommon molecules such as oligosaccharides or rare sugars. However, partly due to the presence of multiple hydroxyl groups with similar reactivities and the structural complexities arising from stereochemistry, the transformation of unprotected sugars to the desired target molecules remains challenging. One such formidable challenge lies in the efficient and selective activation and modification of the C-O bonds in saccharides. In this study, we disclose a modular 2-fold "tagging-editing" strategy that allows for direct and selective editing of C-O bonds of saccharides, enabling rapid preparation of valuable molecules such as rare sugars and drug derivatives. The first step, referred to as "tagging", involves catalytic site-selective installation of a photoredox active carboxylic ester group to a specific hydroxyl unit of an unprotected sugar. The second step, namely, "editing", features a C-O bond cleavage to form a carbon radical intermediate that undergoes further transformations such as C-H and C-C bond formations. Our strategy constitutes the most effective and shortest route in direct transformation and modification of medicines and other molecules bearing unprotected sugars.

Label-free multimodal analysis of copper ions at below permissible exposure limit in the aqueous medium

An anthraimidazoledione based amphiphilic dye molecule was synthesized that shows formation of tuneable charge-transfer state in solution, susceptible to change in pH, polarity and hydrogen bonding ability of the medium. The compound also showed formation of nanoscopic self-assembled structure in water medium. The probe molecule can achieve multimodal detection (colorimetric, fluorimetric and electrochemical) of copper ions as low as 0.3 ppm in the aqueous medium. Addition of copper leads to dose-dependent ratiometric change in solution color from yellow to purple. The mechanistic investigation indicates that the coordination of copper ions was possible via simultaneous engagement of both imidazole nitrogen ends and neighbouring hydroxyl unit. Not only optical property, the changes in microenvironment also influence the selectivity as well as sensitivity of the probe molecule towards Cu2+ ions. Further, the optical probe is used for detection as well as quantification of copper ions in natural water samples without any sample pretreatment. Low-cost, reusable paper strips are developed for rapid, on-location detection of residual Cu2+ in real-life samples.

Multimodal Sensing of Acetate Anion by Using Anthraimidazoledione‐Based Redox‐Active Amphiphilic Dye in Aqueous Environment

AbstractAnthraimidazoledione based amphiphilic dye is synthesized that exhibits pH‐responsive chromogenic response in aqueous environment. This entices us to investigate its anion‐responsive behavior. In pure water, the compound shows no optical response towards anions (poor sensitivity), whereas interaction with multiple anions is witnessed in acetonitrile medium (poor selectivity). Interestingly, changes in solution color from yellow to orange is observed explicitly upon addition of acetate anion, accompanied by fluorescence turn‐off response. Further, it is revealed that the acetate engaged in hydrogen bonding interaction with both imidazole −NH group and hydroxyl unit. The high basicity of acetate anion along with ‘Y‐shaped’ structure might be responsible for such unique selectivity. The present system has been involved in analyzing residual acetate in natural water samples. Low‐cost, reusable paper strips have been designed for equipment free, rapid on‐location detection of acetate.

Use of biocompatible natural product ‘quinine’ for naked-eye sensing of Sarin-surrogate both in solution-state and vapor phase

A fluorescent, biocompatible natural product, quinine (commercially available at low-cost), has been employed for ratiometric, dual-mode sensing of diethyl chlorophosphate (DCP, a sarin surrogate) in the aqueous medium (using pH 7.0 buffer). The addition of DCP induces a rapid (< 30s) change in solution color from colorless to yellow, accompanied by an appearance of intense blue-colored fluorescence (detection limit: 18 nM). Mechanistic investigation indicates phosphorylation of the hydroxyl unit of quinine in the presence of DCP, followed by protonation at the quinoline nitrogen end. The chemodosimetric adduct, so formed, possesses a conformationally-locked structure with a significantly different charge-transfer state as compared to the parent molecule. Such a bifunctional labeling reaction is found to be highly selective towards DCP, no other warfare chemicals, including diethyl cyanophosphate (DCNP, a tabun surrogate) could render any detectable interference. Further, a solid-supported sensing device has been designed as a sustainable strategy for on-site vapor phase detection of DCP.

Density Functional Theory Analysis of the Adsorption Interactions of Carbon Impurities in Coal-associated Kaolinite

Kaolinite is a difficult-to-float clay existing in coal slurries which negatively impacts coal flotation. A better understanding of its adsorption behavior would improve coal-slurry processing. Carbon impurities in the kaolinite can affect this behavior. The appearance and elemental surface composition of the carbon impurities precipitated by kaolinite oxidative treatment were microscopically analyzed, and their chemical speciation and relative C and O contents were probed. The mechanisms of adsorption on the main kaolinite cleavage planes ((001) and (001) surfaces) for two carbon-impurity structural models, a phenolic hydroxyl unit (Ph–OH) and carbon hydroxyl unit (C–OH), were considered using density functional theory methods. The carbon impurities consisted mainly of C and O, with C present mostly as C–C, C–H, and C–O species, and O existing mainly in –OH and C–O structures. Both Ph–OH and C–OH units adsorbed stably on the kaolinite (001) and (001) surfaces through hydrogen bonding between the hydroxyl groups and surfaces. A strong electrostatic attraction occurred between the Ph–OH benzene ring and kaolinite surfaces, whereas the carbon ring in C–OH did not interact with either surface. Finally, for both units, adsorption on the kaolinite (001) surface was more stable than on the (001) surface.

Essential Oils and Eugenols Inhibit Biofilm Formation and the Virulence of Escherichia coli O157:H7.

Enterohemorrhagic Escherichia coli O157:H7 (EHEC) has caused foodborne outbreaks worldwide and the bacterium forms antimicrobial-tolerant biofilms. We investigated the abilities of various plant essential oils and their components to inhibit biofilm formation by EHEC. Bay, clove, pimento berry oils and their major common constituent eugenol at 0.005% (v/v) were found to markedly inhibit EHEC biofilm formation without affecting planktonic cell growth. In addition, three other eugenol derivatives isoeugenol, 2-methoxy-4-propylphenol, and 4-ethylguaiacol had antibiofilm activity, indicating that the C-1 hydroxyl unit, the C-2 methoxy unit, and C-4 alkyl or alkane chain on the benzene ring of eugenol play important roles in antibiofilm activity. Interestingly, these essential oils and eugenol did not inhibit biofilm formation by three laboratory E. coli K-12 strains that reduced curli fimbriae production. Transcriptional analysis showed that eugenol down-regulated 17 of 28 genes analysed, including curli genes (csgABDFG), type I fimbriae genes (fimCDH) and ler-controlled toxin genes (espD, escJ, escR, and tir), which are required for biofilm formation and the attachment and effacement phenotype. In addition, biocompatible poly(lactic-co-glycolic acid) coatings containing clove oil or eugenol exhibited efficient biofilm inhibition on solid surfaces. In a Caenorhabditis elegans nematode model, clove oil and eugenol attenuated the virulence of EHEC.

Preparation, structure study and electrochemistry of layered H2V3O8 materials: High capacity lithium-ion battery cathode

The present study explores H2V3O8 as high capacity cathode material for lithium-ion batteries (LIB's). Despite having high discharge capacity, H2V3O8 material suffers from poor electrochemical stability for prolonged cycle life. Ultra-long H2V3O8 nanobelts with ordered crystallographic patterns are synthesized via a hydrothermal process to mitigate this problem. The growth of the crystal is facile along [001] direction, and the most common surface is (001) as suggested by Wulff construction study. Electrochemical performance of H2V3O8 cathode is tested against Li/Li+ at various current rates. At 50 mA g−1current rate, it delivers a discharge capacity of 308 mAh g−1, whereas, at 3000 mA g−1, an initial discharge capacity of 144 mAh g−1 is observed and stabilized at 100 mAh g−1 till 500 cycles. Further, the density functional theory (DFT) based simulations study of both the pristine and lithiated phase of H2V3O8 cathode materials is undertaken. DFT study reveals the presence of hydrogen as hydroxyl unit in the framework of the host. In correlation, the magnetic property of vanadium atoms is examined in detail with through partial density of states (PDOS) calculation during three stage lithiation processes and evaluating various potential steps involved in lithium insertion.

Nanostructured donor-acceptor self assembly with improved photoconductivity.

Nanostructured supramolecular donor-acceptor assemblies were formed when an unsymmetrical N-substituted pyridine functionalized perylenebisimide (UPBI-Py) was complexed with oligo(p-phenylenevinylene) (OPVM-OH) complementarily functionalized with hydroxyl unit and polymerizable methacrylamide unit at the two termini. The resulting supramolecular complex [UPBI-Py (OPVM-OH)]1.0 upon polymerization by irradiation in the presence of photoinitiator formed well-defined supramolecular polymeric nanostructures. Self-assembly studies using fluorescence emission from thin film samples showed that subtle structural changes occurred on the OPV donor moiety following polymerization. The 1:1 supramolecular complex showed red-shifted aggregate emission from both OPV (∼500 nm) and PBI (∼640 nm) units, whereas the OPV aggregate emission was replaced by intense monomeric emission (∼430 nm) upon polymerizing the methacrylamide units on the OPVM-OH. The bulk structure was studied using wide-angle X-ray diffraction (WXRD). Complex formation resulted in distinct changes in the cell parameters of OPVM-OH. In contrast, a physical mixture of 1 mol each of OPVM-OH and UPBI-Py prepared by mixing the powdered solid samples together showed only a combination of reflections from both parent molecules. Thin film morphology of the 1:1 molecular complex as well as the supramolecular polymer complex showed uniform lamellar structures in the domain range <10 nm. The donor-acceptor supramolecular complex [UPBI-Py (OPVM-OH)]1.0 exhibited space charge limited current (SCLC) with a bulk mobility estimate of an order of magnitude higher accompanied by a higher photoconductivity yield compared to the pristine UPBI-Py. This is a very versatile method to obtain spatially defined organization of n and p-type semiconductor materials based on suitably functionalized donor and acceptor molecules resulting in improved photocurrent response using self-assembly.

Confirmation of the assignment of vibrations of goethite: An ATR and IES study of goethite structure

Transmission electron microscopy (TEM), field emission scanning electron microscopy (FE-SEM/EDS) and X-ray diffraction (XRD) were used to characterize the morphology of synthetic goethite. The behavior of the hydroxyl/water molecular units of goethite and its thermally treated products were characterized using Fourier transform-infrared emission spectroscopy (FT-IES) and attenuated total reflectance–Fourier transform infrared (ATR–FTIR) spectroscopy. The results showed that all the expected vibrational bands between 4000 and 650cm−1 including the resolved bands (3800–2200cm−1) were confirmed. A band attributed to a new type of hydroxyl unit was found at 3708cm−1 and assigned to the FeO–H stretching vibration without hydrogen bonding. This hydroxyl unit was retained up to the thermal treatment temperature of 500°C. On the whole, seven kinds of hydroxyl units, involving three surface hydroxyls, a bulk hydroxyl, a FeO–H without hydrogen bonding, a nonstoichiometric hydroxyl and a reversed hydroxyl were observed, and three kinds of adsorbed water were found in/on goethite.

Thermogravimetric analysis, PXRD, EDX and XPS study of chrysocolla (Cu,Al)2H2Si2O5(OH)4·nH2O-structural implications

Selected chrysocolla mineral samples from different origins have been studied by using PXRD, SEM, EDX and XPS. The XRD patterns show that the chrysocolla mineral samples are non-diffracting and no other phases are present in the minerals, thus showing the chrysocolla samples are pure. SEM analyses show the chrysocolla surfaces are featureless. EDX analyses enable the formulae of the chrysocolla samples to be calculated.The thermal decomposition of the mineral chrysocolla has been studied using a combination of thermogravimetric analysis and derivative thermogravimetric analysis. Five thermal decomposition mass loss steps are observed for the chrysocolla from Arizona (a) at 125°C with the loss of water, (b) at 340°C with the loss of hydroxyl units, (c) at 468.5°C with a further loss of hydroxyls, (d) at 821°C with oxygen loss and (e) at 895°C with a further loss of oxygen. The thermal analysis of the chrysocolla from Congo shows mass losses at 125, 275.3, 805.6 and 877.4°C and for the Nevada chrysocolla, mass loss steps at 268, 333, 463, 786.0 and 817.7°C are observed. The thermal analysis of spertiniite is very different from that of chrysocolla and thermally decomposes at around 160°C.XPS shows that there are two different copper species present, one which is bonded to oxygen and one to a hydroxyl unit. The O 1s is broad and very symmetrical suggesting two O species of equal number. The bond energy of 102.9eV for the Si 2p suggests that it is in the form of a silicate. The bond energy is much higher for silicas around ∼103.5eV. The reported value for silica gel has Si 2p at 103.4eV. The combination of TG, PXRD, EDX and XPS adds to our fundamental knowledge of the structure of chrysocolla.

DNA-binding and anti-oxidation properties of binuclear lanthanide(III) complexes of 8-hydroxyquinoline-7-carbaldehyde-(isonicotinyl)hydrazone

Binuclear complexes [LnL(NO3)(H2O)2]2 were prepared from the Schiff base 8-hydroxyquinoline-7-carbaldehyde-(isonicotinyl)hydrazone (H2L) and equivalent molar amounts of Ln(NO3)3 · 6H2O (Ln = La3+, Nd3+, Sm3+, Eu3+, Gd3+, Dy3+, Ho3+, Er3+, Yb3+), respectively. The ligand is dibasic tetradentate and the dimerization occurs through the phenolate oxygen atoms leading to a central four-membered (LnO)2-ring. The ligand and all the Ln(III) complexes can bind to calf thymus DNA through intercalation with binding constants of 105–106 (mol L−1)−1, and they show strong scavenging abilities on hydroxyl radicals and superoxide radicals. The values of SC 50 of Ln(III) complexes for HO• and are 2.344−13.33 and 4.459−28.48 µmol L−1, respectively. Ln(III) complexes present stronger binding abilities to DNA and stronger anti-oxidation properties than ligand. Complex containing hydroxyl unit shows stronger scavenging abilities on hydroxyl radical, while complex containing N-heteroaromatic substituent shows stronger scavenging abilities on superoxide radicals. Furthermore, earlier rare metal complexes show stronger scavenging abilities on both hydroxyl radicals and superoxide radicals.

Suppressive effects of liquid crystal compounds on the growth of U937 human leukemic monocyte lymphoma cells

BackgroundThe aim of this study was to evaluate the biological and pharmaceutical activities of 14 amphiphilic liquid-crystalline compounds (LCs), i.e, phenylpyrimidine derivatives possessing D-glucamine and cyanobiphenyl derivatives with a terminal hydroxyl unit.ResultsThe cytotoxic properties of the LCs on the cell growth, cell cycle distribution, and cell signaling pathway of U937 human leukemic monocyte lymphoma cells were assessed by flow cytometry and western blot analysis. Some LCs showed cytostatic effects, suppressing cell growth via S-phase arrest and without apoptosis in U937 cells. To investigate the mechanisms of the LC-induced S-phase arrest, proteins relevant to cell cycle regulation were investigated by western blot analysis. The rate of LC-induced S-phase arrest was congruent with the decreased expression of MCM2, cyclin A, cyclin B, CDK2, phospho-CDK1 and Cdc25C. Observed changes in cell cycle distribution by LC treated might be caused by insufficient preparation for G2/M transition. Considering the structure of the LCs, the rod-like molecules displaying cytotoxicity against U937 cells possessed flexible spacers with no bulky polar group attached via the flexible spacer.ConclusionsOur results revealed that some LCs showed cytotoxic properties against non-solid type tumor human leukemic cells via LC-induced S-phase arrest and decreasing expression of several cell cycle related proteins.

Bonding of Hard Disk Lubricants with OH-Bearing End Groups

Typical lubricants for magnetic hard disks comprise the central perfluoropolyether section and the short hydrocarbon end groups bearing hydroxyl unit(s). It had been shown earlier that chemical bonding of these lubricants to the carbon overcoat of disks involves (1) dangling bonds shielded inside the carbon, (2) transfer of the hydrogen atom of the hydroxyl unit to a dangling bond site, and (3) attachment of the remaining alkoxy system, R–CF2–CH2–O·, to the carbon surface as a pendant ether unit. Dangling bonds at or near the surface react immediately with H2O or O2 in the atmosphere. It follows that, in order to bond, the hydrocarbon end group must move into crevices of the carbon film. It was postulated that the bonding rate would depend on the length of the hydrocarbon end-group, –(CH2) n –OH. The longer the hydrocarbon sector is, the faster and the more extensively the bonding would proceed. Bonding rates were examined for a set of samples differing only in the dimension of the hydrocarbon end-group. Results clearly in accordance with the postulate were obtained. The sample set included two novel lubricants, D-2TX2 and D-2TX4, with the following end-groups, –O–CF2–CH2–O–(CH2) n=2,4–OH. Excellent bonding rate, coverage, and potential anticorrosion property were revealed for these lubricants.

The high-pressure behavior of micas: Vibrational spectra of muscovite, biotite, and phlogopite to 30 GPa

The infrared spectra of natural samples of muscovite, biotite, and phlogopite are characterized to pressures of ~30 GPa, as is the Raman spectrum of muscovite to ~8 GPa. Both far-infrared and mid-infrared data are collected for muscovite, and mid-infrared data for biotite and phlogopite. The response of the hydroxyl vibrations to compression differs markedly between the dioctahedral and trioctahedral micas: the hydrogen bonding in dioctahedral environments increases with pressure, as manifested by shifts to lower frequency of the hydroxyl-stretching vibrations, whereas cation-hydrogen repulsion likely produces shifts to higher frequency of the hydroxyl vibrations within trioctahedral environments. An abrupt decrease in frequency and increase in band width of the hydroxyl-stretching vibration in muscovite is observed at pressures above ~18–20 GPa, implying that the previously documented pressure-induced disordering is associated with the local environment and shifts in location of the hydroxyl unit in this material. The far-infrared vibrations of muscovite indicate that its compressional mechanism changes above 5–8 GPa, as the K-O stretching vibration with a zero-pressure frequency near 112 cm−1 shifts in its pressure dependence from 6.9 cm−1/GPa below this pressure range to 0.78 cm−1/GPa above it. Thus, it appears that the magnitude of interlayer compression is decreased above this pressure, and hence that the compression of muscovite may become less strongly anisotropic. The mid-infrared bands that are primarily produced by vibrations of the tetrahedral layer broaden under pressure in both muscovite and biotite: within biotite, a spectral region that may be associated with higher coordination of tetrahedral cations increases in amplitude above about 25 GPa. The corresponding bands in phlogopite undergo less broadening, and their behavior is fully reversible on decompression.

Competition between micro-segregation and anti-parallel alignment of an amphiphilic rod-like liquid crystal

Recently, we reported that a rod-like molecule, 4-[4-(7-hydroxyheptyloxy)phenyl]-1-(4-hexylphenyl)-2,3-difluorobenzene, exhibited a nematic phase with a layered structure and smectic C phases consisting of three states. We prepared a homologous series of the rod-like molecules in which a 2,3-difluoro-1,4-diphenylbenzene unit and a hydroxyl unit are connected via a flexible methylene spacer. We investigated their physical properties using polarised optical microscopy (POM), differential scanning calorimetry (DSC) and X-ray diffraction (XRD). Although they showed nematic, smectic A and smectic C phases, the phase structures were found to depend on the flexible spacer length. Those compounds possessing a shorter spacer length than a heptyl unit exhibited bilayered smectic A and smectic C phases, whereas those possessing a longer spacer length than a heptyl unit showed conventional monolayered smectic A and smectic C phases. A nematic phase with a smectic-like layer ordering was observed for the compound possessing an octyl unit. The structure–property relations of the amphiphilic compounds are discussed.

Theoretical Study of Amino Acid Interaction with Metal Organic Frameworks

We have investigated by density functional theory the interaction of representative amino acids such as glycine and tyrosine with a suitably functionalized organic linker of the IRMOF-14 metal−organic framework for various sites and ways of approach. It was found that the only active site with nonmarginal interaction energy is the one introduced by the strategic replacement of a linker hydrogen by a hydroxyl unit. Such replacement, which is experimentally tested and implemented, is capable of producing intermediate magnitude hydrogen bonds with interaction energies of 9.8 kcal/mol for glycine and 10.8 kcal/mol for tyrosine. The type and magnitude of these interactions, which have been also verified by second-order Møller−Plesset perturbation theory, allow appreciable binding without overbinding. This is very promising for possible pharmaceutical applications of MOFs.

Suppressive effects of liquid crystal compounds on the growth of the A549 human lung cancer cell line

The aim of this study was to evaluate the biological activity and pharmacological activity of several amphiphilic liquid-crystalline compounds (LCs), i.e. phenylpyrimidine derivatives possessing D-glucamine and cyanobiphenyl derivatives with a terminal hydroxyl unit, to explore novel anti-cancer functions of the LCs. The anti-cancer properties of the LCs were investigated in A549 human lung cancer cells by assessing cell growth, cell cycle distribution, and cell signaling pathways using a flow cytometer and a Western blot analysis. In addition, the effect of LCs on the growth of WI-38 normal fibroblasts was examined. Consequently, the phenylpyrimidine derivatives and cyanobiphenyl derivatives showed cytostatic effects, causing the suppression of cell growth through G1 phase arrest in A549 cells. Further analyses using phenylpyrimidine derivatives and precursors of a cyanobiphenyl compound demonstrated the structure-activity relationships. One of the phenylpyrimidine derivatives inhibited A549 growth without any toxicity to normal fibroblasts. As a result, a novel pharmacological function was hypothesized to be inherent in the structure of the LCs themselves, and the dependence of the tumor-specific activity on the hydrophobic group of phenylpyrimidine derivatives therefore remains an interesting issue. Our results suggest the possibility that the LCs themselves may act as a novel type of chemotherapeutic agent.

Grafting Lubricant Molecular Chains to the Carbon Overcoat

It was conceived and demonstrated that irradiation of magnetic disks coated with PFPE (perfluoropolyether) lubricants terminated with a carboxylic group at one terminus with long-UV (254 nm) would lead to grafting, via a bona fide C–C chemical bond, of genuine PFPE molecular chains to the carbon overcoat all at one terminus with all the remaining chain segments being free to sway. The water contact angle of disks coated with PFPE lubricants terminated with end-groups having hydroxyl unit(s) (e.g., Z-dol and Z-tetraol) decreases gradually, after the initial contact of the droplet, reaching an asymptote in 20–30 s. The gradual temporal change is accounted for by shifting of the equilibrium disposition of hydroxyl units of the lubricant molecules from that determined by the interaction with the surface of the carbon overcoat to that determined by the interaction with surfaces of both the carbon overcoat and the liquid droplet. The water contact angle of disks prepared by the presently conceived photo-grafting method is high (>110 degrees) and shows no temporal change. In a preliminary spin-stand drag test, disks with PFPE chains photo-grafted by this method and also the heads (for the read/write process) with similar photo-grafted PFPE chains exhibited extraordinary durability.

FTIR study of ageing epoxy resin reinforced by reactive graphitic nanofibers

AbstractWe previously developed a novel modified epoxy matrix for macrocomposites using reactive graphitic nanofibers (r‐GNFs), which showed improved mechanical properties. This article is devoted to study the efficacy of the r‐GNFs against the damage due to exposition of the matrix to hygrothermal environment and UV radiation. Moisture sorption characteristics of the pure epoxy and nanoepoxy were investigated and all kinds of matrices showed similar absorption behavior. Both diffusion and relaxation processes in sorption were observed. DSC curves of nonaged specimens of all concentrations confirmed that samples were not fully cured and r‐GNFs lowered the curing degree. The effects of ageing were studied through the changes of molecular conformation by Fourier Transform infrared spectroscopy (FTIR). The results show that UV radiation assists in post‐curing of the matrices. Hydroxyl unit, carbonyl unit, and epoxide unit were chosen to study the degradation. It is observed that the degradation due to UV radiation is more severe compared with that due to hygrothermal expose. It also reveals that r‐GNFs resist the degradation of the epoxy resin; particularly, the nanoepoxy with 0.3 wt % of r‐GNFs has the highest ageing resistance, which is in agreement with our previously tested results of mechanical properties. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007

Z-dol and carbon overcoat: the bonding mechanism

Molecular dispositions of Z-dol (linear perfluoropolyether with hydroxyl termini, –O–CF2–CH2–OH) applied over the carbon overcoat of magnetic hard disks are often depicted by an arrangement based on the hydrogen bonding interaction between the hydroxyl ends and some polar units of the carbon surface. The hydrogen bonding interaction is weak. The arrangement based on this mechanism is attained rapidly, but is slowly replaced (if partially) by a bona fide chemical bond. The issue of the exact nature of this chemical bond has been left unanswered in most of the reports. Past works deemed to have explored and elucidated the identity of the bond in question are gathered, reviewed and deductively presented. The review, we believe, clearly shows that the bonding in question involves (1) dangling bonds shielded within the sputter-deposited carbon, (2) transfer of the hydrogen atom of the hydroxyl unit of Z-dol to the dangling bond site, and (3) attachment of the remaining alkoxy system, Z–O–CF2–CH2–O•, to the carbon surface as a pendant ether unit. The Z-dol moiety thus attached is held by a bona fide chemical bond, and cannot be replaced by water molecules nor removed by solvent extraction.