Synthesis and characterization of novel polyimides derived from 2‐amino‐5‐(4‐aminophenyl)‐thiazole

A new kind of aromatic unsymmetrical diamine monomer containing thiazole ring, 2‐amino‐5‐(4‐aminophenyl)‐thiazole (AAPT), was synthesized. A series of novel polyimides were prepared by polycondensation of AAPT with various aromatic dianhydrides by one‐step polyimidation process. The synthesized polyimides had inherent viscosity values of 0.36–0.69 dL/g and were easily dissolved in highly dipolar solvents. Meanwhile, strong and flexible polyimide films were obtained, which have good thermal and thermo‐oxidative stability with the glass transition temperatures (T_g) of 276.7–346.1°C, the temperature at 5% weight loss of 451–492°C in nitrogen and 422–440°C in air, as well as have outstanding mechanical properties with the tensile strengths of 94–122 MPa, elongations at breakage of 5–18%. These films also had dielectric constants of 3.12–3.38 at 10 MHz. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Microbial conversion of androst‐1,4‐dien‐3,17‐dione by Mucor racemosus to hydroxysteroid‐1,4‐dien‐3‐one derivatives

BACKGROUND: A large number of bacterial, fungal and microalgal species are able to bio‐transform steroid compounds. Among them, fungi from the Mucor genus have been shown to mediate hydroxylation, oxidation, and desaturation by the double bond formation and epoxidation of various steroid substances. Mucor racemocus has not been studied for its ability to modify androst‐1,4‐dien‐3,17‐dione, a pharmaceutically important steroid precursor. RESULTS: The filamentous fungus M. racemosus was applied for bioconversion of androst‐1,4‐dien‐3,17‐dione (ADD, I ) in a 5‐day fermentation. Microbial metabolites were purified chromatographically and identified on the basis of their spectral data as 17β‐hydroxyandrost‐1,4‐dien‐3‐one ( II ), 14α‐hydroxyandrost‐1,4‐dien‐3,17‐dione ( III ), 15α‐hydroxyandrost‐1,4‐dien‐3,17‐dione ( IV ), 15α,17β‐dihydroxyandrost‐1,4‐dien‐3‐one ( V ), 14α,17β‐dihydroxyandrost‐1,4‐dien‐3‐one ( VI ), and 6β,17β‐dihydroxyandrost‐1,4‐dien‐3‐one ( VII ). CONCLUSION: Observed modifications included hydroxylation at C‐6β, C‐14α, C‐15α positions and 17‐carbonyl reduction. The best fermentation conditions for production of hydroxysteroid‐1,4‐dien‐3‐one derivatives were found to be 25 °C at 150 rpm for 5 days with a substrate concentration of 0.5 g L^?1. Copyright © 2009 Society of Chemical Industry     

Design,Synthesis, and Biological Evaluation of (S)‐Valine Thiazole‐Derived Cyclic and Noncyclic Peptidomimetic Oligomers as Modulators of Human P‐Glycoprotein (ABCB1)

Multidrug resistance caused by ATP binding cassette transporter P‐glycoprotein (P‐gp) through extrusion of anticancer drugs from the cells is a major cause of failure in cancer chemotherapy. Previously, selenazole‐containing cyclic peptides were reported as P‐gp inhibitors and were also used for co‐crystallization with mouse P‐gp, which has 87 % homology to human P‐gp. It has been reported that human P‐gp can simultaneously accommodate two to three moderately sized molecules at the drug binding pocket. Our in silico analysis, based on the homology model of human P‐gp, spurred our efforts to investigate the optimal size of (S)‐valine‐derived thiazole units that can be accommodated at the drug binding pocket. Towards this goal, we synthesized varying lengths of linear and cyclic derivatives of (S)‐valine‐derived thiazole units to investigate the optimal size, lipophilicity, and structural form (linear or cyclic) of valine‐derived thiazole peptides that can be accommodated in the P‐gp binding pocket and affects its activity, previously an unexplored concept. Among these oligomers, lipophilic linear ( 13 ) and cyclic trimer ( 17 ) derivatives of QZ59S‐SSS were found to be the most and equally potent inhibitors of human P‐gp (IC₅₀=1.5 μM ). As the cyclic trimer and linear trimer compounds are equipotent, future studies should focus on noncyclic counterparts of cyclic peptides maintaining linear trimer length. A binding model of the linear trimer 13 within the drug binding site on the homology model of human P‐gp represents an opportunity for future optimization, specifically replacing valine and thiazole groups in the noncyclic form.     

Molecular Recognition of Two 2,4‐syn‐Functionalized (S)‐Glutamate Analogues by the Kainate Receptor GluK3 Ligand Binding Domain

The kainate receptors are the least studied subfamily of ionotropic glutamate receptors. These receptors are thought to have a neuromodulatory role and have been associated with a variety of disorders in the central nervous system. This makes kainate receptors interesting potential drug targets. Today, structures of the ligand binding domain (LBD) of the kainate receptor GluK3 are only known in complex with the endogenous agonist glutamate, the natural product kainate, and two synthetic agonists. Herein we report structures of GluK3 LBD in complex with two 2,4‐syn‐functionalized (S)‐glutamate analogues to investigate their structural potential as chemical scaffolds. Similar binding affinities at GluK3 were determined for the 2‐(methylcarbamoyl)ethyl analogue (K_i=4.0 μM ) and the 2‐(methoxycarbonyl)ethyl analogue (K_i=1.7 μM ), in agreement with the similar positioning of the compounds within the binding pocket. As the binding affinity is similar to that of glutamate, this type of Cγ substituent could be used as a scaffold for introduction of even larger substituents reaching into unexplored binding site regions to achieve subtype selectivity.     

4‐Hydroxy‐3‐methyl‐6‐(1‐methyl‐2‐oxoalkyl)pyran‐2‐one Synthesis by a Type III Polyketide Synthase from Rhodospirillum centenum

The purple photosynthetic bacterium Rhodospirillum centenum has a putative type III polyketide synthase gene (rpsA). Although rpsA was known to be transcribed during the formation of dormant cells, the reaction catalyzed by RpsA was unknown. Thus we examined the RpsA reaction in vitro, using various fatty acyl‐CoAs with even numbers of carbons as starter substrates. RpsA produced tetraketide pyranones as major compounds from one C_10–14 fatty acyl‐CoA unit, one malonyl‐CoA unit and two methylmalonyl‐CoA units. We identified these products as 4‐hydroxy‐3‐methyl‐6‐(1‐methyl‐2‐oxoalkyl)pyran‐2‐ones by NMR analysis. RpsA is the first bacterial type III PKS that prefers to incorporate two molecules of methylmalonyl‐CoA as the extender substrate. In addition, in vitro reactions with ¹³C‐labeled malonyl‐CoA revealed that RpsA produced tetraketide 6‐alkyl‐4‐hydroxy‐1,5‐dimethyl‐2‐oxocyclohexa‐3,5‐diene‐1‐carboxylic acids from C_14–20 fatty acyl‐CoAs. This class of compounds is likely synthesized through aldol condensation induced by methine proton abstraction. No type III polyketide synthase that catalyzes this reaction has been reported so far. These two unusual features of RpsA extend the catalytic functions of the type III polyketide synthase family.     

Synthesis of novel 3‐hetaryl‐substituted 6‐ and 8‐hydroxybenzo[f]coumarin derivatives

Eight novel 3‐hetaryl‐substituted 6‐ and 8‐hydroxybenzo[f]iminocoumarin compounds were synthesised by the reaction of 2,5‐dihydroxynaphthaldehydes or 2,7‐dihydroxynaphthaldehydes with 2‐cyanomethylbenzo‐thiazole, 2‐cyanomethylbenzoimidazole, 1‐methyl‐2‐cyanomethylbenzoimidazole and 2‐cyanomethyl‐4‐phenylthiazole. The iminocompounds obtained were hydrolysed with hydrochloric acid to the benzo[f]coumarins. Becaue of the high reactivity of the iminocoumarins, only mixtures which also contained the corresponding coumarin compounds were isolated. The absorption and steady‐state fluorescence characteristics of the benzo[f]coumarins (benzo[f]chromen‐2‐ones) synthesised were studied in ethanol and in toluene.     

Polymerization of 4‐(4′‐N‐1,8‐naphthalimidophenyl)‐1,2,4‐triazolidine‐3,5‐dione with diisocyanates

4‐(4′‐Aminophenyl)‐1,2,4‐triazolidine‐3,5‐dione ( 1 ) was reacted with 1,8‐naphthalic anhydride ( 2 ) in a mixture of acetic acid and pyridine (3 : 2) under refluxing temperature and gave 4‐(4′‐N‐1,8‐naphthalimidophenyl)‐1,2,4‐triazolidine‐3,5‐dione ( NIPTD ) ( 3 ) in high yield and purity. The compound NIPTD was reacted with excess n‐propylisocyanate in N,N‐dimethylacetamide solution and gave 1‐(n‐propylamidocarbonyl)‐4‐[4′‐(1,8‐naphthalimidophenyl)]‐1,2,4‐triazolidine‐3,5‐dione ( 4 ) and 1,2‐bis(n‐propylamidocarbonyl)‐4‐[4′‐(1,8‐naphthalimidophenyl)]‐1,2,4‐ triazolidine‐3,5‐dione ( 5 ) as model compounds. Solution polycondensation reactions of monomer 3 with hexamethylene diisocyanate ( HMDI ), isophorone diisocyanate ( IPDI ), and tolylene‐2,4‐diisocyanate ( TDI ) were performed under microwave irradiation and conventional solution polymerization techniques in different solvents and in the presence of different catalysts, which led to the formation of novel aliphatic‐aromatic polyureas. The polycondensation proceeded rapidly, compared with conventional solution polycondensation, and was almost completed within 8 min. These novel polyureas have inherent viscosities in a range of 0.06–0.20 dL g^?1 in conc. H₂SO₄ or DMF at 25°C. Some structural characterization and physical properties of these novel polymers are reported. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2861–2869, 2003     

Novel organosoluble poly(amide‐imide‐imide)s synthesized from new tetraimide‐dicarboxylic acid by condensation with 4,4′‐oxydiphthalic anhydride, 1,4‐bis(4‐amino‐2‐trifluoromethylphenoxy)benzene,trimellitic anhydride,and various aromatic diamines

A new monomer of tetraimide‐dicarboxylic acid (IV) was synthesized by starting from ring‐opening addition of 4,4′‐oxydiphthalic anhydride, trimellitic anhydride, and 1,4‐bis(4‐amino‐2‐trifluoromethylphenoxy)benzene at a 1:2:2 molar ratio in N‐methyl‐2‐pyrrolidone (NMP). From this new monomer, a series of novel organosoluble poly(amide‐imide‐imide)s with inherent viscosities of 0.7–0.96 dL/g were prepared by triphenyl phosphite activated polycondensation from the tetraimide‐diacid with various aromatic diamines. All synthesized polymers were readily soluble in a variety of organic solvents such as NMP and N,N‐dimethylacetamide, and most of them were soluble even in less polar m‐cresol and pyridine. These polymers afforded tough, transparent, and flexible films with tensile strengths ranging from 99 to 125 MPa, elongations at break from 12 to 19%, and initial moduli from 1.6 to 2.4 GPa. The thermal properties and stability were also good with glass‐transition temperatures of 236–276°C and thermogravimetric analysis 10 wt % loss temperatures of 504–559°C in nitrogen and 499–544°C in air. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2854–2864, 2006     

MT1‐Selective Melatonin Receptor Ligands: Synthesis,Pharmacological Evaluation,and Molecular Dynamics Investigation of N‐{[(3‐O‐Substituted)anilino]alkyl}amides

The design of compounds selective for the MT₁ melatonin receptor is still a challenging task owing to the limited knowledge of the structural features conferring selectivity for the MT₁ subtype, and only few selective compounds have been reported so far. N‐(Anilinoalkyl)amides are a versatile class of melatonin receptor ligands that include nonselective MT₁/MT₂ agonists and MT₂‐selective antagonists. We synthesized a new series of N‐(anilinoalkyl)amides bearing 3‐arylalkyloxy or 3‐alkyloxy substituents at the aniline ring, looking for new potent and MT₁‐selective ligands. To evaluate the effect of substituent size and shape on binding affinity and intrinsic activity, both flexible and conformationally constrained derivatives were prepared. The phenylbutyloxy substituent gave the best result, providing the partial agonist 4 a , which was endowed with high MT₁ binding affinity (pK_i=8.93) and 78‐fold selectivity for the MT₁ receptor. To investigate the molecular basis for agonist recognition, and to explain the role of the 3‐arylalkyloxy substituent, we built a homology model of the MT₁ receptor based on the β₂ adrenergic receptor crystal structure in its activated state. A binding mode for MT₁ agonists is proposed, as well as a hypothesis regarding the receptor structural features responsible for MT₁ selectivity of compounds with lipophilic arylalkyloxy substituents.     

Synthesis and characterization of poly(ester‐ether‐imide)s derived from 5‐(4‐trimellitimidophenoxy)‐1‐trimellitimido naphthalene

A series of novel aromatic poly(ester‐ether‐imide)s with inherent viscosity values of 0.44–0.74 dL g^?1 were prepared by the diphenylchlorophosphate‐activated direct polycondensation of an imide ring‐containing diacid namely 5‐(4‐trimellitimidophenoxy)‐1‐trimellitimido naphthalene ( 1 ) with various aromatic dihydroxy compounds in the presence of pyridine and lithium chloride. Owing to comparison of the characterization data, an ester‐containing model compound ( 2 ) was also synthesized by the reaction of 1 with phenol. The model compound 2 and the resulted polymers were fully characterized by FT‐IR and NMR spectroscopy. The ultraviolet λ_max values of the poly(ester‐ether‐imide)s were also determined. The resulting polymers exhibited an excellent organosolubility in a variety of high polar solvents such as N,N‐dimethylacetamide, N,N‐dimethylformamide, dimethyl sulfoxide, and N‐methyl‐2‐pyrrolidone. They were soluble even in common less polar organic solvents such as pyridine, m‐cresol, and tetrahydrofuran on heating. Crystallinity of the polymers was estimated by means of wide‐angle X‐ray diffraction. The resulted polymers exhibited nearly an amorphous nature. From differential scanning calorimetry thermograms, the polymers showed glass‐transition temperatures between 221 and 245°C. Thermal behaviors of the obtained polymers were characterized by thermogravimetric analysis, and the 10% weight loss temperatures of the poly(ester‐ether‐imide)s were found to be over 410°C in nitrogen. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

2,3‐Dihydro‐1‐Benzofuran Derivatives as a Series of Potent Selective Cannabinoid Receptor 2 Agonists: Design,Synthesis, and Binding Mode Prediction through Ligand‐Steered Modeling

We recently discovered and reported a series of N‐alkyl‐isatin acylhydrazone derivatives that are potent cannabinoid receptor 2 (CB₂) agonists. In an effort to improve the druglike properties of these compounds and to better understand and improve the treatment of neuropathic pain, we designed and synthesized a new series of 2,3‐dihydro‐1‐benzofuran derivatives bearing an asymmetric carbon atom that behave as potent selective CB₂ agonists. We used a multidisciplinary medicinal chemistry approach with binding mode prediction through ligand‐steered modeling. Enantiomer separation and configuration assignment were carried out for the racemic mixture for the most selective compound, MDA7 (compound 18 ). It appeared that the S enantiomer, compound MDA104 (compound 33 ), was the active enantiomer. Compounds MDA42 (compound 19 ) and MDA39 (compound 30 ) were the most potent at CB₂. MDA42 was tested in a model of neuropathic pain and exhibited activity in the same range as that of MDA7. Preliminary ADMET studies for MDA7 were performed and did not reveal any problems.     

Synthesis and biological activity of medium molecular weight polymers containing 3,6‐endo‐methylene‐1,2,3,6‐tetrahydrophthalimidobutanoyl‐5‐fluorouracil

A new monomer, 3,6‐endo‐methylene‐1,2,3,6‐tetrahydrophthalimidobutanoyl‐5‐fluorouracil (ETBFU), was synthesized by reaction of 3,6‐endo‐methylene‐1,2,3,6‐tetrahydrophthalimidobutanoyl chloride and 5‐fluorouracil. The homopolymer of ETBFU and its copolymers with acrylic acid (AA) or vinyl acetate (VAc) were prepared by photopolymerization using 2,2‐dimethoxy‐2‐phenylacetophenone as an initiator at 25 °C. The synthesized ETBFU and its polymers were identified by FTIR, ¹H NMR and ¹³C NMR spectroscopies. The ETBFU content in poly(ETBFU‐co‐AA) and poly(ETBFU‐co‐VAc) was 43 and 14 mol%, respectively. The apparent number‐average molecular weight (M_n) of the polymers determined by GPC ranged from 8400 to 11 300. The in vitro cytotoxicity of the samples against mouse mammary carcinoma (FM3A), mouse leukaemia (P388), and human histiocytic lymphoma (U937) cancer cell lines decreased in the order 5‐FU ≥ ETBFU > poly(ETBFU) > poly(ETBFU‐co‐AA) > poly(ETBFU‐co‐VAc). The in vivo antitumour activity of the polymers against Balb/C mice bearing sarcoma 180 tumour cells was greater than that of 5‐fluorouracil at all doses tested. © 2000 Society of Chemical Industry     

Synthetic and Biological Studies of Tubulin Targeting C2‐Substituted 7‐Deazahypoxanthines Derived from Marine Alkaloid Rigidins

C2‐aryl‐ and C2‐alkyl‐7‐deazahypoxanthines as analogues of marine alkaloid rigidins were prepared utilizing novel synthetic methods developed for the construction of the pyrrolo[2,3‐d]pyrimidine ring system. The new compounds exhibited sub‐micromolar to nanomolar antiproliferative potencies against a panel of cell lines including in vitro models for drug‐resistant tumors, such as glioblastoma, melanoma and non‐small‐cell lung cancer. A selected representative C2‐methyl‐7‐deazahypoxanthine was found to inhibit microtubule dynamics in cancer cells, lending evidence for tubulin targeting as a mode of action for these compounds in cancer cells. The results of the docking studies utilizing the colchicine site on β‐tubulin were consistent with the observed structure–activity relationship data, including an important finding that derivatization at C2 with linear alkyl groups leads to the retention of activity, thus permitting the attachment of a biotin‐containing linker for the subsequent proteomics assays. Because many microtubule‐targeting compounds are successfully used to fight cancer in the clinic, the reported antitubulin rigidin analogues have significant potential as new anticancer agents.     

Synthesis and properties of TLCPs with 2,6‐naphthalene‐based mesogen,polymethylene spacer,and nonlinear 4,4′‐thiodiphenyl links

A series of new thermotropic main‐chain liquid crystalline copolyesters were prepared by polycondensation of 2,6‐naphthalenedicarbonyl chloride, 4,4′‐thiodiphenol, and α,ω‐alkanediols (n = 4–10) in diphenyl ether at 200°C. Thermal transition behaviors of these copolyesters were investigated by differential scanning calorimetry. Moreover, their thermal stabilities and mesomorphic textures were studied by thermogravimetric analysis and polarizing optical microscopy, respectively. Corresponding model compounds with terminal mesogenic units and central polymethylene spacers were also synthesized for comparison. Both copolymers and model compounds exhibit odd–even dependency of melting temperatures, transition enthalpy (ΔH_m), and entropy (ΔS_m) on the number of methylene units in the spacer. However, the odd–even effects in model compounds are much more distinctive. Nematic mesophases are the only texture observed in melts, except the model compounds with longer methylene units (n = 8, 10), in which smectic mesophases can be observed. The T_m values of the copolyesters (TDP/HD = 1/1) are between 233 and 259°C, depending on spacer length. The initial decomposition temperatures of the copolyesters are above 419°C under N₂ atmosphere. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1536–1546, 2002     

Synthesis and characterization of α‐butyl‐omega‐{3‐[2‐hydroxy‐3‐(N‐methyl‐N‐hydroxy‐ ethylamino)propoxy]propyl}polydimethylsiloxane

A novel synthesis path for the monotelechelic polydimethylsiloxane with a diol‐end group, α‐butyl‐omega‐{3‐[2‐hydroxy‐3‐(N‐methyl‐N‐hydroxyethylamino)propoxy]propyl}polydimethylsiloxane, is described in this article. The preparation included three steps, which were anionic ring‐opening polymerization, hydrosilylation, and epoxy addition. The structure and polydispersity index of the products were analyzed and confirmed by FTIR, ¹H NMR, ¹³C NMR, H? H, and C? H. Correlated Spectroscopy and gel permeation chromatography. The results demonstrated that each step was successfully carried out and the targeted products were accessed in all cases. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis,Characterization, and Energetic Properties of N‐Rich Salts of the 4,5‐Dicyano‐2H‐1,2,3‐triazole Anion

The synthesis and characterization of the 4,5‐dicyano‐2H‐1,2,3‐triazole anion in its 5‐aminotetrazole, 1,5‐diaminotetrazole, and 1,5‐diamino‐4‐methyl‐tetrazole salts are reported. All compounds were characterized by IR, ¹H NMR, and ¹³C NMR spectroscopy, as well as elemental analyses. Their thermal decompositions were investigated by TG‐DSC. The densities, combustion heats, and sensitivity properties were tested. Additionally, enthalpies of formation, detonation pressures, detonation velocities, and heats of detonation were calculated. The compounds have potential application in the energetic materials field.     

Structure–Activity Relationships of 1,2‐Disubstituted Benzimidazoles: Selective Inhibition of Heme Oxygenase‐2 Activity

Devising ways to up‐ or down‐regulate heme oxygenase activity is attracting much interest as a strategy for the treatment of a variety of disorders. With a view of obtaining compounds that exhibit high potency and selectivity as inhibitors of the heme oxygenase‐2 (HO‐2) isozyme (constitutive) relative to the heme oxygenase‐1 (HO‐1) isozyme (inducible), several 1,2‐disubstituted 1H‐benzimidazoles were designed and synthesized. Specifically, analogues were synthesized in which the C2 substituent was the following: (1H‐imidazol‐1‐yl)methyl, (N‐morpholinyl)methyl, cyclopentylmethyl, cyclohexylmethyl, or (norborn‐2‐yl)methyl. Compounds with the cyclic system in the C2 substituent being a carbocyclic ring, especially cyclohexyl or norborn‐2‐yl, and the N1 substituent being a ring‐substituted benzyl group, especially 4‐chlorobenzyl or 4‐bromobenzyl, best exhibited the target criteria of high potency and selectivity toward inhibition of HO‐2. The new candidates should be useful pharmacological tools and may have therapeutic applications.     

Synthesis,Structure–Activity,and Structure–Stability Relationships of 2‐Substituted‐N‐(4‐oxo‐3‐oxetanyl) N‐Acylethanolamine Acid Amidase (NAAA) Inhibitors

N‐Acylethanolamine acid amidase (NAAA) is a cysteine amidase that preferentially hydrolyzes saturated or monounsaturated fatty acid ethanolamides (FAEs), such as palmitoylethanolamide (PEA) and oleoylethanolamide (OEA), which are endogenous agonists of nuclear peroxisome proliferator‐activated receptor‐α (PPAR‐α). Compounds that feature an α‐amino‐β‐lactone ring have been identified as potent and selective NAAA inhibitors and have been shown to exert marked anti‐inflammatory effects that are mediated through FAE‐dependent activation of PPAR‐α. We synthesized and tested a series of racemic, diastereomerically pure β‐substituted α‐amino‐β‐lactones, as either carbamate or amide derivatives, investigating the structure–activity and structure–stability relationships (SAR and SSR) following changes in β‐substituent size, relative stereochemistry at the α‐ and β‐positions, and α‐amino functionality. Substituted carbamate derivatives emerged as more active and stable than amide analogues, with the cis configuration being generally preferred for stability. Increased steric bulk at the β‐position negatively affected NAAA inhibitory potency, while improving both chemical and plasma stability.     

Turn‐on chemosensors for silver ions based on oligomers with diaza‐16‐crown 6‐ether receptors and aromatic fluorophore end groups

The reaction of N‐(2,4‐dinitrophenyl)pyridinium chloride ( 1 ), diaza‐18‐crown 6‐ether (DA18C6) and 2,5‐bis(aminophenyl)‐1,3,4‐oxadiazole ( 2 ) caused the opening of the pyridinium ring and yielded an ionic oligomer (oligomer‐1) comprising a 5‐DA18C6‐penta‐2,4‐dienylideneammonium chloride main chain and 2‐(4‐aminophenyl)‐5‐phenyl‐1,3,4‐oxadiazole or 2‐(4‐N‐phenylpyridinium)‐5‐phenyl‐1,3,4‐oxadiazole end groups. Accordingly, the reaction of 1 , DA18C6 and 2,7‐diaminofluorene ( 3 ) yielded oligomer‐2. The structures of oligomer‐1 and oligomer‐2 were determined by comparing their ¹H NMR spectra with those of model compounds, which were synthesized by the 1:1 reaction of 1 with 2 or 3 . Oligomer‐1 and oligomer‐2 exhibited weak bluish‐green photoluminescence (PL) before the inclusion of Ag⁺ in the DA18C6 receptor, after which they exhibited strong bluish‐green PL. These observations can be explained by the occurrence of photoinduced electron transfer in the oligomers. Copyright © 2011 Society of Chemical Industry