Dihydroxybiphenyl Research Articles

Structural and antibacterial assessment of two distinct dihydroxy biphenyls encapsulated with β-cyclodextrin supramolecular complex

β-Cyclodextrin plays a vital role in biological application because it can enhance the stability and solubility of the guest molecules in the supramolecular inclusion complexes. Moreover, the β-Cyclodextrin inclusion complex has control-releasing behavior and lower toxicity than bare guest molecules. To improve the solubility and stability properties of two structurally different fluorescent guest molecules, namely 2,2′-dihydroxy biphenyl and 3,3′-dihydroxy biphenyls, they involve the β-Cyclodextrin inclusion complex process. Optical measurements clearly described the efficient binding through the changes in the absorbance and emission intensities of guest molecules in the presence of β-Cyclodextrin. The Job's plot from absorbance measurements reveals the 1:1 stochiometric ratio of binding of guests and the β-Cyclodextrin host. The FT-IR spectra of the solid complex show the characteristic stretching and bending vibrations from both the guests and the host molecule. The 1HNMR spectra of the inclusion complex promote downfield shifting of guest molecule protons upon binding with the β-Cyclodextrin host. The solid complex prepared using the solution method exhibits superior antibacterial activity against both gram-positive and gram-negative bacteria compared to the kneading and physical mixing methods.

Structure and properties of aromatic naphthalene thermotropic liquid crystal copolyester/MWCNT composites

Aromatic naphthalene thermotropic liquid crystal copolyesters (N-TLCP) have strong intermolecular forces and possess excellent comprehensive properties. In this study, the N-TLCP/MWCNT nanocomposites derived from 6-hydroxy-2-naphthoic acid (HNA), 2,6-naphthalene dicarboxylic acid (NDA), terephthalic acid (TA), 4,4′-dihydroxy biphenyl (BP) and carboxyl MWCNT were prepared via in situ “one-pot” melt polymerization method. The structure and properties of N-TLCP/MWCNT composites were fully analyzed. The interaction between MWCNT and TLCP matrix was confirmed by FTIR, XPS, Raman spectrum and rheometric measurements; and the strong interaction was observed for addition of a small amount of MWCNT (<0.5 wt%), which was attributed to the fact that the functional group COOH on the surface of MWCNTs enhances the dispersion state of the CNTs and molecular interaction through hydrogen bond/chemical covalent bonds. As a result, the glass transition temperature, melting temperature, thermal stability and mechanical properties of the N-TLCP/MWCNT composite was improved. However, more addition of MWCNT would tend to aggregate and impact the molecular weight and structure of the N-TLCP by the chemical reaction between its COOH group and OH group of the N-TLCP, which is not favor for improving the mechanical properties.

Biochemical and genetic characterization comparison of four extradiol dioxygenases in Rhizorhabdus wittichii RW1.

Rhizorhabdus (previously Sphingomonas) wittichii RW1 uses a diverse array of aromatic organic compounds as energy and carbon sources, including some extremely recalcitrant compounds such as dibenzo-p-dioxin and dibenzofuran. Extradiol dioxygenases play a key role in the metabolism of dibenzofuran (DBF), dibenzo-p-dioxin (DBD), PCBs, and various other aromatic compounds. In this study, a detailed kinetic analysis of four extradiol dioxygenases identified in R. wittichii RW1 (DbfB, Edo2, Edo3, and Edo4) showed all of them to be typical 2,3dihydroxybiphenyl (DHB) dioxygenases with DHB as preferred substrate (kcat/Km values of 0.13-188 (µM -1s-1)) and only slightly lower activity against trihydroxybiphenyl (THB) whereas monocyclic substrates were, to different extents, poor substrates due to high km values. All extradiol dioxygenases analyzed were subject to mechanism-based inactivation by 2,2`,3-trihydroxybiphenylether (THBE) the intermediate of DBD degradation. However, Edo4 was superior as reflected by the relatively high partition ratio and the comparably low efficiency of inactivation. Significant differences were observed with respect to their inactivation by 3-chlorocatechol. The absence of any significant mechanism-based inactivation makes Edo3 a perfect candidate for being recruited for chlorobiphenyl degradation where inactivation of extradiol dioxygenases by this intermediate creates significant metabolic problems. KEY POINTS: • Characterization of additional extradiol dioxygenases encoded by RW1 • Identification of differences in 2,2`,3-trihydroxybiphenylether transformation • Identification of differences in inhibition by 3-chlorocatechol.

Photoluminescent studies of 2, 2’-dihydroxybiphenyl, ethylenediamine - formaldehyde copolymer

Polymer resin-II (2,2’-DBPEDF) synthesized by the condensation polymerization of 2,2’-dihydroxybiphenyl (DBP), ethylenediamine (ED) and formaldehyde (F) in acidic medium with molar ratio 2:1:3 of monomer and refluxing in oil bath at 120°C for 5 hr. Synthesized copolymer as a ligand is combined with metal particles such as Ni2+, Cu2+ and Zn2+ ions is in 2:1 molar proportion to get metal complex. The reaction has been finished with refluxed at 60°C for three hour. Composition and structure of organic polymer resin-II have been determined by elemental analysis and molecular weight determination by non-aqueous conductometric titration. The UV-visible, FTIR, proton nuclear magnetic resonance and surface feature and crystalline behaviour of ligand and its complexes were analysed by SEM. Newly synthesized copolymer with metal complexes with copper and zinc metal may be used as supporting material for luminescence 2,2’-DBPEDF-Cu show higher photoluminescence than 2,2’-DBPEDF-Zn.

Break of Metal-organic Chains Induced by 4，4′-Dihydroxybiphenyl on Surfaces

Break of Metal-organic Chains Induced by 4，4′-Dihydroxybiphenyl on Surfaces

Potentiality of PARAFAC approaches for simultaneous determination of N-acetylcysteine and acetaminophen based on the second-order data obtained from differential pulse voltammetry

N-acetylcysteine (N-AC) has widespread application such as pharmaceutical drug and nutritional supplement. Its adverse effects are rash, urticaria, and itchiness and large doses of N-AC could potentially cause damage to the heart and lungs. Therefore, in this work, a sensitive voltammetric sensor based on a carbon paste electrode modified with silica nano particles (i.e. Mobil Composition of Matter (No. 41) modified with Boron Trifluoride or BF3@MCM-41) with a combination of 4,4′-dihydroxybiphenyl (DHB) (BF3@MCM-41/DHB/CPE) was designed for determination of N-AC. The electrochemical oxidation of N-AC was examined using various techniques such as cyclic voltammetry (CV), chronoamperometry and differential pulse voltammetry (DPV). Under the optimum conditions, some parameters such as electron transfer coefficient (α) and heterogeneous rate constant (ks) were estimated for N-AC. Due to the use of N-AC for the treatment of acetaminophen (AC) overdose, the application of modified electrode was investigated for the simultaneous determination of N-AC and AC in blood serum and tablet samples. Since, the signals of these species overlap and due to the presence of interfering species in blood samples, the simultaneous determination of mentioned species is difficult or impossible. To overcome this challenge, parallel factor analysis (PARAFAC) was used for the analysis of the complex matrices to obtain the spectral profile of each component and interference. To achieve this goal, electrochemical second-order data were generated using a simple change in pulse height of differential pulse voltammetry. The results of the presently proposed strategy for the real samples analysis are similar to those obtained with HPLC. Thus, the proposed method has acceptable performance for simultaneous determination of the two species in real samples.

Thermal degradation kinetics of structurally diverse poly(bispropargyl ethers-bismaleimide) blends

Structurally diverse bispropargyl ethers using resorcinol, quinol, 4,4′-dihydroxy biphenyl, bisphenol-A, 4,4′- dihydroxy diphenyl ketone, 4,4′-dihydroxy diphenylsulphone, trimethyl indane bisphenol and tetramethyl spirobiindane bisphenol were prepared by using phase transfer catalyst. Synthesized materials were separately blended with 4,4′-bismaleimido diphenyl methane (BMIM) in mole ratios (0.5:0.5). The materials were thermally cured and the structural characterisation and the thermal properties of these cross-linked materials are investigated using Fourier-transform infrared (FTIR) spectrophotometer and thermogravimetric analyzer (TGA). Among the different materials investigated polyMRPE, polyMBPEBPA and polyMSPE show higher onset degradation temperature of 300 °C indicating higher thermal stability. The degradation kinetics is investigated using Flynn-Wall-Ozawa (FWO), Vyazovkin (VYZ) and Friedman (FRD) methods. Amongst the various cured materials investigated, the activation energy (Ea-D) values obtained for polyMRPE and polyMKPE were observed to increase continuously from α = 0.2 to 0.8 and the values range from 199 kJ/mol to 245 kJ/mol and 153 kJ/mol to 295 kJ/mol respectively. The crosslinked materials resulting from these bispropargyl monomers definitely need more energy for bond cleavage due to the presence of more aromatic units. The volatile products obtained during the thermal degradation of the polymers were analyzed using thermogravimetric-Fourier transform infrared analyses (TG-FTIR). The phenols, substituted phenols, carbon monoxide, carbon dioxide and small amount of aniline were found to be the major products during thermal degradation of these cured blends.

Decomposition and combustion studies of phosphine oxide containing aromatic polyethers

A comparative study of the decomposition and combustion behavior of systematically varied linear polyether analogs is reported. Properties of aromatic polyethers of bisphenol A/or 4,4′-dihydroxy biphenyl with bis(4-fluorophenyl) derivatives with phosphorus, –CF3 and methoxy –OCH3 constituents were systematically evaluated. All polyethers were synthesized by nucleophilic aromatic polycondensation. The polymers obtained covered a wide range of weight average molar masses (40,000–125,000 g/mol) as determined by size exclusion chromatography with multi-angle light scattering detection. FTIR and NMR spectroscopy revealed formation of the desired polymer structure of the linear polyarylene ethers. All polymers were easily soluble in common organic solvents, thus enabling processing from solution. Film casting from dichloromethane solution yielded transparent, free standing films with high mechanical stability (tensile strengths up to 63 MPa, E-moduli up to 2.5 GPa and elongations at break up to 35%). The thermal decomposition under nitrogen was accessed by thermogravimetry (TGA) and TGA combined with infrared spectroscopy, while the combustion was examined by pyrolysis combustion flow calorimetry (PCFC). The fire behavior was examined for one polymer (P3) by limiting oxygen index that revealed that the phosphine oxide moieties have a measurable influence on flame retardancy compared to the PSU control.

High-temperature matrix resins based on bispropargyl ethers (BPEs) – part 2

Structurally diverse bispropargyl ethers (BPEs) using resorcinol, quinol, 4,4′-dihydroxy biphenyl, bisphenol-A, 4,4′-dihydroxy diphenyl ketone, 4,4′-dihydroxy diphenylsulphone, trimethyl indane bisphenol and tetramethyl spirobiindane bisphenol were synthesized, and it was separately blended with 4,4′-bismaleimido diphenyl methane (BMIM) in mole ratios (0.5:0.5). The structural characterizations of the materials are carried out using Fourier transform infrared and nuclear magnetic resonance studies. Differential scanning calorimetric analysis shows that the difference in the melting characteristics and decrease in the curing window for different BPEs were caused by the incorporation BMIM. Addition of BMIM to BPEs reduces the heat liberated during the thermal curing. The curing kinetics is investigated using Flynn–Wall–Ozawa, Vyazovkin and Friedman methods. Amongst the various BPEs investigated, the activation energy ( Ea) values obtained from spirobiindane BPE (SPIPE) behaves entirely in a different manner compared to all other materials investigated. The apparent Ea values for SPIPE was observed to increase with increasing extent of reaction up to 0.2–0.5 and then the Ea values decrease with increasing extent of reaction up to 0.55–0.8. The Ea for the polymer blends obtained by the incorporation of BMIM with different BPEs shows nearly linear increase in the Ea value, and the rate of increase is influenced by the structure of the aromatic spacer present in between the propargyl groups.

Studies on inclusion complexation between 4,4′-dihydroxybiphenyl and β-cyclodextrin by experimental and theoretical approach

The inclusion complex formation between 4,4′-dihydroxybiphenyl (DHBP) and β-cyclodextrin (β-CD) in aqueous state were studied by UV–Visible spectroscopy, Fluorescence spectroscopy and electrochemical study (cyclic voltammetry, CV). The solid state complex between β-CD and DHBP were characterized by FT-IR, XRD techniques and SEM morphological studies. The β-CD: DHBP inclusion complex obtained by molecular docking studies was in good correlation with the results obtained through experimental methods. The binding constant of ‘β-CD: DHBP’ inclusion complex was calculated using Benesi–Hildebrand plot at 303K. The experimental results indicated that the inclusion process is an exergonic and spontaneous process. The point energy, stabilization energy upon complexation and frontier molecular orbital’s were obtained. The calculation results correlates well with the docking and experimental observations.

Synthesis and characterization of main-chain liquid crystalline copolyesters containing phosphaphenanthrene side-groups

Abstract A series of thermotropic main-chain liquid crystalline copolyesters P1–P5 containing 2-(6-oxide-6H-dibenz〈c,e〉〈1,2〉oxaphosphorin-6-yl)-1,4-dihydroxyphenylene (ODOPB) as non-mesogenic unit and 4,4′-dihydroxybiphenyl (DB) as mesogenic unit were prepared by polycondensation with sebacoyl chloride. The thermal and mesogenic properties were characterized by differential scanning calorimetry (DSC), polarizing optical micrography (POM), X-ray diffraction (XRD) and thermogravimetric analysis (TGA). It was found that introducing of ODOPB into polyester decreased the melting temperature (Tm) and the isotropic temperature (Ti). The copolyesters P1–P5 exhibited mesomorphic properties even when the molar ratio of the non-mesogenic monomer ODOPB to mesogenic monomer DB reached 6:4 in feed. For explaining the effect of DOPO group on the mesomorphic properties, the X-ray diffraction analysis of a low molecular weight modal compound containing ODOPB was carried out and the results show that the DOPO side-group is parallel with the most-adjacent benzene ring in the main-chain, which reveals the small effect of ODOPB on the mesogenic structure of polyesters. The thermal analysis showed that the incorporation of phosphorus-containing moieties increase the residual char of the formed liquid crystalline polymers. The thermal stability, however, decreases because the O P–O bond is less stable than the common C–C bond.

Monomer/polymer Schiff base copper(II) complexes for catalytic oxidative polymerization of 2,2′-dihydroxybiphenyl

Catalytic oxidative polymerization of 2,2′-dihydroxybiphenyl (DHBP) was performed by using both the Schiff base monomer-Cu(II) complex and Schiff base polymer-Cu(II) complex compounds as catalysts and hydrogen peroxide as oxidant, respectively. The dependence of monomer conversion and molecular weight distribution on various reaction parameters, including time, temperature, solvent as well as the amount of catalyst and oxidant were investigated. The structure of the poly-2,2′-dihydroxybiphenyl (PDHBP) was confirmed by UV-vis, IR, 1H and 13C NMR spectroscopy techniques. The electrochemical and thermal properties of PDHBP were also studied. DSC data revealed that PDHBP was amorphous. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2977–2984, 2009

Blends of Aromatic Polyethers Bearing Polar Pyridine Units and Their Evaluation as High Temperature Polymer Electrolytes

AbstractAromatic polyethers containing polar pyridine units in the main chain have been synthesized using different difluoride monomers. Copolymers of 2,5‐(4′,4″dihydroxy biphenyl)‐pyridine and 3,3′,5,5′‐tetramethyl‐[1,1′‐biphenyl]‐4,4′‐diol with bis(4‐fluorophenyl) sulfone or phenyl phosphine oxide difluoride or decafluorobiphenyl (PTMPySF, PTMPyPO, PTMPyDF) were synthesized. These polymeric structures despite their common structural characteristics, showed totally different behavior in terms of solubility and acid doping ability. Blends of these copolymers have been prepared in order to be evaluated in terms of fuel cell relevant parameters like acid doping ability and conductivity. In most cases flexible membranes were obtained by solution casting. The acid doping ability was controlled based on the blend constituents and composition. The doped membranes exhibited high conductivity values, in the range of 10−3 S/cm at room temperature which is increased at 2.5 × 10−2 S/cm at temperatures up to 180 °C.

Non-isothermal degradation kinetics of poly (2,2′-dihydroxybiphenyl)

Catalytic oxidative polymerization of 2,2′-dihydroxybiphenyl (DHBP) was performed by using Schiff base polymer-Cu (II) complex and hydrogen peroxide as catalyst and oxidant, respectively. According to size exclusion chromatography (SEC) analysis, the number-average molecular weight (Mn), weight-average molecular weight (Mw) and polydispersity index (PDI) values of poly (2,2′-dihydroxybiphenyl) (PDHBP) were found to be 37,500, 90,000 g mol−1 and 2.4, respectively. The thermal degradation kinetics was investigated by thermogravimetric analysis in dynamic nitrogen atmosphere at four different heating rates: 5, 10, 15 and 20 °C min−1. The derivative thermogravimetry curves of PDHBP showed that its thermal degradation process had one weight-loss step. The apparent activation energies of thermal decomposition for PDHBP as determined by Tang, Flynn–Wall–Ozawa (FWO), Kissenger–Akahira–Sunose (KAS), Coats–Redfern (CR) and Invariant kinetic parameter (IKP) methods were 109.1, 109.0, 110.0, 108.4 and 109.8 kJ mol−1, respectively. The mechanism function and pre-exponential factor were determined by master plots and Criado–Malek–Ortega method. The most likely decomposition process was a Dn Deceleration type in terms of the CR, master plots and Criado–Malek–Ortega results.

Synthesis and drug release properties of poly(ethylene oxide) segmented polysulfone copolymers

A series of poly(ethylene oxide) (PEO) segmented polysulfone copolymers with different PEO content has been successfully synthesized via condensation polymerization of 4,4′-dichlorodiphenylsulfone (DCDPS), chlorine-end-capped poly(ethylene oxide) (PEO-Cl 2)) and 4,4′-dihydroxybiphenyl (DHBP) in N, N-dimethylacetamide (DMAc) in the presence of anhydrous potassium carbonate at 160 °C for 20 h. The resulting copolymers showed high molecular weights (Mn = 28,000–40,200 Da) and relatively narrow molecular weight distributions (Mw/Mn = 1.57–1.87). They are well soluble in common organic solvents such as chloroform and tetrahydrofuran. Films with high tensile strength (38–50 MPa) and good elasticity of elongation (elongation at break: 190–430%) were prepared by solution cast from the copolymer solutions in chloroform. Sirolimus and paclitaxel were used as drugs and their release kinetics were investigated. For both drugs, the release rate was strongly influenced by the PEO content of the polymer films, i.e., PSF–PEO films with higher PEO content showed larger drug release rate. Film swelling due to liquid sorption is mainly responsible for the drug release.

Synthesis and properties of new aromatic poly(ester‐imide)s derived from 4‐p‐biphenyl‐2,6‐bis(4‐trimellitimidophenyl) pyridine and various dihydroxy compounds

AbstractA novel class of wholly aromatic poly(ester‐imide)s, having a biphenylene pendant group, with inherent viscosities of 0.32–0.49 dL g−1 was prepared by the diphenylchlorophosphate‐activated direct polyesterification of the preformed imide‐ring‐containing diacid, 4‐p‐biphenyl‐2,6‐bis(4‐trimellitimidophenyl)pyridine (1) with various aromatic dihydroxy compounds in the presence of pyridine and lithium chloride. A reference diacid, 2,6‐bis(trimellitimido)pyridine (2) without a biphenylene pendant group and two phenylene rings in the backbone, was also synthesized for comparison purposes. At first, with due attention to structural similarity and to compare the characterization data, a model compound (3) was synthesized by the reaction of compound 1 with two mole equivalents of phenol. Moreover, the optimum condition of polymerization reactions was obtained via a study of the model compound synthesis. All of the resulting polymers were characterized by Fourier transform infrared and 1H NMR spectroscopy and elemental analysis. The ultraviolet λmax values of the poly(ester‐imide)s were also determined. All of the resulting polymers exhibited excellent solubility in common organic solvents, such as pyridine, chloroform, tetrahydrofuran, and m‐cresol, as well as in polar organic solvents, such as N‐methyl‐2‐pyrrolidone, N,N‐dimethylacetamide, N,N‐dimethylformamide, and dimethyl sulfoxide. The crystalline nature of the polymers obtained was evaluated by means of wide‐angle X‐ray diffraction. The resulting poly(ester‐imide)s showed nearly an amorphous nature, except poly(ester‐imide) derived from 4,4′‐dihydroxy biphenyl. The glass transition temperatures (Tg) of the polymers determined by differential scanning calorimetry thermograms were in the range 298–342 °C. The 10% weight loss temperatures (T10%) from thermogravimetric analysis curves were found to be in the range 433–471 °C in nitrogen. Films of the polymers were also prepared by casting the solutions. Copyright © 2006 Society of Chemical Industry

Novel Polymer Electrolyte Membrane, Based on Pyridine Containing Poly(ether sulfone), for Application in High‐Temperature Fuel Cells

AbstractSummary: Novel poly(aryl ether sulfone) copolymers containing 2,5‐biphenylpyridine and tetramethyl biphenyl moieties were synthesized by polycondensation of 4‐fluorophenyl sulfone with 2,5‐(4′,4″ dihydroxy biphenyl)pyridine and tetramethyl biphenyl diol. Copolymers with different molecular weights and different monomer compositions were obtained. These copolymers exhibit excellent film‐forming properties, mechanical integrity, and high modulus up to 250 °C, high glass transition temperatures (above 280 °C) as well as high thermal stability up to 400 °C. In addition to the above properties required for PEMFC application, this novel material shows high oxidative stability and acid doping ability, enabling proton conductivity in the range of 10−2 S · cm−1 above 130 °C.Synthesis of copolymers with high acid uptake and ionic conductivity.magnified imageSynthesis of copolymers with high acid uptake and ionic conductivity.

Photocatalysed reaction of few selected organic systems in presence of titanium dioxide

The photocatalysed reaction of five selected organic systems, namely 2,2′-dinitro biphenyl ( 1), N, N′-dimethyl-4-nitroso aniline ( 2), 4-dimethyl amino benzaldehyde ( 3), phthalaldehyde ( 4) and tetramethyl benzoquinone ( 5) has been investigated in acetonitrile/water mixture in the presence of titanium dioxide and oxygen. An attempt has been made to identify the products formed during the photooxidation process through GC/MS analysis technique. The photolysis of 2,2′-dinitro biphenyl ( 1) leads to the formation of 2-hydroxy-2′-nitro biphenyl ( 6), 2,2′-dihydroxy biphenyl ( 7) and 2-biphenyl amine ( 11); whereas, N, N′-dimethyl-4-nitroso aniline ( 2) gave rise to N, N′-dimethyl-4-nitro aniline ( 14) and N, N′-dimethyl-1,4-benzenediamine ( 15). However, the photolysis of 4-dimethyl amino benzaldehyde ( 3) yielded only a demethylated product ( 18). The illumination of phthalaldehyde ( 4), on the other hand, led to the formation of two products such as 1(3H)-isobenzofuranone ( 24) and 2-formyl-benzoic acid ( 21). Two intermediate products, tetramethyl hydroquinone ( 35) and 2,5-furandione-3,4-dimethyl ( 34) have been identified in case of tetramethyl benzoquinone ( 5). The products have been identified by comparing the molecular ion and mass fragmentation peaks of the products with those reported in the GC/MS library. A probable mechanism for the formation of the products has been proposed.

Multicyclic Poly(ether ketone)s Obtained by Polycondensation of 2,6,4‘-Trifluorobenzophenone with Various Diphenols

2,6,4‘-Trifluorobenzophenone (TFB) was polycondensed with silylated 4,4‘-dihydroxybiphenyl (DHBP) or silylated bisphenol A in N-methylpyrrolidone by means of K2CO3 as catalyst and HF acceptor. At c...

A physiological study on growth and dibenzothiophene (DBT) desulfurization characteristics of Gordonia sp. CYKS1

Physiological characteristics of DBT desulfurization and cell growth ofGordonia sp. CYKS1 were investigated. It exhibited a preference to ethanol in a medium containing two carbon sources, ethanol and one of the carbohydrates used, glucose, sucrose, maltose, and galactose although it consumed both carbon sources simultaneously. Cell growth on ethanol or glucose followed the Monod kinetics. The optimal range of pH for the desulfurization of DBT and the cell growth was 7 to 8. The desulfurization rate decreased about 30% at pH 6, and no significant desulfurization or cell growth was observed at pH 5. As the initial DBT concentration increased up to 1.5 mM, the desulfurization rate also increased while no significant changes in the growth rate were observed. The maximum desulfurization rate was 12.50 μmol L-1 h-1 at an initial DBT concentration of 1.5 mM. Cell growth and desulfurization activity were severely inhibited by the presence of 2-hydroxybiphenyl (2-HBP). When 0.05 mM of 2-HBP was added at the beginning, both of the desulfurization rate and cell growth rate decreased about 20%. It was found that cell growth and desulfurization were completely inhibited in the presence of 2-HBP at 0.15 mM or a higher concentration. The inhibition by 2,2′-dihydroxybiphenyl (DHBP) was less severe than 2-HBP. About 80% of desulfurization activity was retained in the presence of 2,2′-DHBP at 0.4 mM.