Rare earth (Eu, Tb) mesoporous hybrids with calix[4]arene derivative covalently linking MCM-41: Physical characterization and photoluminescence property

MCM-41 mesoporous silica has been functionalized with two kinds of macrocylic calixarene derivatives Calix[4] and Calix[4]Br (Calix[4]=P-tert-butylcalix[4]arene, Calix[4]Br=5.11,17.23-tetra-tert-butyl-25.27-bihydroxy-26.28-bibromopropoxycalix[4]arene) through condensation approach of tetraethoxysilane (TEOS) in the presence of the cetyltrimethylammonium bromide (CTAB) surfactant as a template. Novel organic-inorganic mesoporous luminescent hybrid containing RE³⁺ (Eu³⁺, Tb³⁺) complexes covalently attached to the functionalized ordered mesoporous MCM-41, which are designated as RE-Calix[4]-MCM-41 and RE-Calix[4]Br-MCM-41, respectively, are obtained by sol-gel process. It is found that they all have high surface area, uniform in the mesostructure and good crystallinity. Measurement of the photoluminescence properties show the mesoporous material covalently bonded Tb³⁺ complexes (Tb-Calix[4]-MCM-41 and Tb-Calix[4]Br-MCM-41) exhibit the stronger characteristic emission of Tb³⁺ and longer lifetime than the corresponding Eu-containing materials Eu-Calix[4]-MCM-41 and Eu-Calix[4]Br-MCM-41 due to the triplet state energy of modified organic ligands Calix[4]-Si and Calix[4]Br-Si match with the emissive energy level of Tb³⁺ very well.     

An approach to the synthesis of chemically modified bisazocalix[4]arenes and their extraction properties

Bisazocalix[4]arenes [N,N′-bis(5-azo-25,26,27-tribenzoyloxy-28-hydroxycalix[4]arene)benzene (1), N,N′-bis(5-azo-25,26,27-tribenzoyloxy-28-hydroxycalix[4]arene)biphenyl (2) and N,N′-bis(5-azo-25,26,27-tribenzoyloxy-28-hydroxycalix[4]arene)-2,2′-dinitro biphenyl (3)] have been synthesized from 25,26,27-tribenzoyloxy-28-hydroxycalix[4]arene by diazocoupling with the corresponding aromatic diamines (p-phenylenediamine, 4,4′-diamino biphenyl and 4,4′-diamino-2,2′-dinitrobiphenyl). Extraction studies of bisazocalix[4]arenes 1, 2, and 3 show no difference in their extraction behavior and selectivity, whereas azocalix[4]arenes are a poor extractant for heavy metal cations. The absorption spectra of the prepared bisazocalix[4]arenes are discussed, both the effect of varying pH and solvent upon the absorption ability of bisazocalix[4]arenes.     

Synthesis of new Di-, Tetra-, and hexahydropyrazolo[3,4-e][1,4]diazepine derivatives

Alkaline hydrolysis of 5-(2,2-diethoxyethyl-, aroylmethyl-, or ethoxycarbonylmethyl)-1H-pyrazolo-[3,4-e]pyrimidin-4(5H)-ones gave 5-amino-N-(2,2-diethoxyethyl-, aroylmethyl-, or carboxymethyl)-1H-pyrazole-4-carboxamides which underwent cyclization to the corresponding 7-hydroxy-5,6,7,8-tetrahydropyrazolo-[3,4-e][1,4]diazepin-4(1H)-ones, 5,6-dihydropyrazolo[3,4-e][1,4]diazepin-4(1H)-ones, and 1,5,6,8-tetrahydropyrazolo[3,4-e][1,4]diazepine-4,7-diones. Reduction of the cyclization products with NaBH4 and LiAlH4 afforded 5,6,7,8-tetrahydropyrazolo[3,4-e][1,4]diazepin-4(1H)-ones and 1,4,5,6,7,8-hexahydropyrazolo[3,4-e]-[1,4]diazepines.     

Pyrolytic desulfurization ring contraction of condensed thiadiazines as a general route towards pyrazoloazines and pyrazoloazoles with a bridgehead (ring junction) nitrogen atom

Pyrolytic conversion of [1,2,4]triazino[3,4-b][1,3,4]thiadiazin-4-ones, [1,3,4]thiadiazino[2,3-b]quinazolin-10-ones and [1,2,4]triazolo[3,4-b][1,3,4]thiadiazines into their corresponding pyrazolo[5,1-c][1,2,4]triazin-4-ones, pyrazolo[4,3-b]quinazolin-9-ones and pyrazolo[5,1-b][1,2,4]triazoles via desulfurization ring contraction is described. The starting condensed 1,3,4-thiadiazines were prepared from the corresponding readily available 4-amino-3-thioxo-1,2,4-triazin-5(4H)-ones, 3-amino-2,3-dihydro-2-thioxoquinazolin-4(1H)-one and 4-amino-3(2H)-thioxo-1,2,4-triazoles upon reaction with the appropriate α-haloketones in two steps, or directly in one step in ethylpyridinium tetrafluoroborate (ionic liquid, IL).     

(1+1) or (2+2) Coupling for bis(tosyloxyethoxy)benzenes with calix[4]arene and thiacalix[4]arene

As bifunctional reagents, bis(tosyloxyethoxy)benzenes can react with p-tert-butylcalix[4]arene or p-tert-butylthiacalix[4]arene to afford intramolecularly bridged (1+1) or intermolecularly bridged (2+2) products. It was found that the bridging pattern strongly depended on the structure of bis(tosyloxyethoxy)benzene and the kind of calixarene. For the ortho-isomer of bis(tosyloxyethoxy)benzene, intramolecularly bridged calix[4]arene and thiacalix[4]arene were the main products. For the para-isomer, the bridging reaction was in a (2+2) fashion. As for the meta-isomer, double thiacalix[4]arene and intramolecularly bridged calix[4]crown were synthesized.     

Enantioselective microbial reduction of 6-oxo-8-[4-[4-(2-pyrimidinyl)-1-piperazinyl]butyl]-8-azaspiro[4.5]decane-7,9-dione

The enantioselective microbial reduction of 6-oxo-8-[4-[4-(2-pyrimidinyl)-1-piperazinyl]butyl]-8-azaspiro[4.5]decane-7,9-dione 1 to either of the corresponding (R)- or (S)-6-hydroxy-8-[4-[4-(2-pyrimidinyl)-1-piperazinyl]butyl]-8-azaspiro[4.5]decane-7,9-diones 2 and 3 is described.     

Synthesis of 7-iodo(arylsulfanyl)methyl-7,8-dihydro-[1,3]thiazolo[2,3-i]purinium pentaiodide (perchlorates) and their transformation into 4-amino-5-(1,3-thiazol-2-yl)imidazole derivatives

Intramolecular electrophilic cyclization of 6-allylsulfanylpurine by the action of iodine and arenesulfenyl chlorides gave 7-iodomethyl-7,8-dihydro[1,3]thiazolo[2,3-i]purin-6-ium pentaiodide and 7-arylsulfanylmethyl-7,8-dihydro[1,3]thiazolo[2,3-i]purin-6-ium perchlorates, respectively. 7-Iodomethyl-7,8-dihydro-[1,3]thiazolo[2,3-i]purin-6-ium iodide reacted with sodium and potassium alkoxides to produce alkyl N-[5-(4-methyl-1,3-thiazol-2-yl)-1H-imidazol-4-yl]formimidates, and its reaction with secondary cyclic amines afforded 5-(4-methyl-1,3-thiazol-2-yl)-N-[morpholin-4-yl(or piperidin-1-yl)methylidene]-1H-imidazol-4-amines. Successive treatment of 7-arylsulfanylmethyl-7,8-dihydro[1,3]thiazolo[2,3-i]purin-6-ium perchlorates with sodium acetate and morpholine led to the formation of 5-(4-arylsulfanylmethyl-4,5-dihydro-1,3-thiazol-2-yl)-N-(morpholin-4-ylmethylidene)-1H-imidazol-4-amines.     

Synthesis and properties of mono-O-[(N-(aminoalkyl)aminocarbonyl)-methoxy]thiacalix[4]arenes and novel mono-O-bridged bisthiacalix[4]arene

A simple method for thiacalix[4]arene O-monoamide preparation with high yields using 5,11,17,23-tetra-tert-butyl-28-(ethoxycarbonyl)methoxy-2,8,14,20-tetrathiacalix[4]arene reaction with diaminoalkanes is reported. The solid state cyclization reaction of the acylethylenediamines function of 5,11,17,23-tetra-tert-butyl-28-O-[(N-(2-aminoethyl)aminocarbonyl)-methoxy]thiacalix[4]arene leading to the formation of the 5,11,17,23-tetra-tert-butyl-28-[2-methoxy-imdazoline]thiacalix[4]arene compound is described for the first time for the calixarene macrocycle family. Finally, preliminary results show that O-mono-amide-thiacalixarene derivatives are promising candidates for the production of self-assembled materials and efficient precursors for the synthesis of bisthiacalix[4] arenes.     

A regioselective 1,3-dipolar cycloaddition for the synthesis of novel spiro-chromene thiadiazole derivatives

A variety of 4′-(4-R-phenyl)-4-(methylthio)-2′-phenyl-2′H-spiro[chromene-2,5′-[1,2,3]thiadiazole] 5a–d and 5′-(4-R-phenyl)-4-(methylthio)-3′-phenyl-3′H-spiro[chromene-2,2′-[1,3,4]thiadiazole] 6a–d were synthesized regioselectively through the reaction of 4-(methylthio)-2H-chromene-2-thione 2 with diarylnitrilimines under refluxing dry chloroform. Whilst the reaction of 4-(allylthio)-2H-chromene-2-thione 3 with diarylnitrilimines under similar reaction conditions afforded the corresponding 4-(allylthio)-5′-(4-R-phenyl)-3′-phenyl-3′H-spiro[chromene-2,2′-[1,3,4]thiadiazole] 7a–d and 5-(4-R-phenyl)-2′-methyl-3-phenyl-2′,3′-dihydro-3H-spiro[[1,3,4]thiadiazole-2,4′-thieno[3,2-c]chromene] 9a–d as two unisolable diastereoisomeric forms. The structures of the obtained spiro cycloadduct thiadiazoles have been assigned by means of spectroscopic measurements.     

Stereoselective synthesis of dihydrothiadiazinoazines and dihydrothiadiazinoazoles and their pyrolytic desulfurization ring contraction

Intramolecular base catalyzed C-C bond formation led to exclusive stereoselective syntheses of trans-6,7-dihydro-5H-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazines, trans-7,8-dihydro-6H-[1,2,4]triazino[3,4-b][1,3,4]thiadiazin-4-ones, and trans-3,4-dihydro-2H-[1,3,4]thiadiazino[2,3-b]quinazolin-10-one. trans-6,7-Dihydro-5H-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazines isomerize slowly in CDCl₃ and more rapidly in DMSO-d₆ into the corresponding cis-stereoisomers. The other trans-6,7-dihydro-[1,3,4]thiadiazines isomerize also in DMSO-d₆ into the corresponding cis-stereoisomers. Pyrolytic conversion of these heterocyclic condensed dihydrothiadiazines into their corresponding pyrazolo[5,1-b][1,2,4]triazoles, pyrazolo[5,1-c][1,2,4]triazin-4-ones and pyrazolo[4,3-b]quinazolin-9-ones via desulfurization ring contraction is described.     

Ab initio and density functional studies of cooperative hydrogen bonding in calix[4]-and calix[6]arenes

The cone conformation of C ₄ symmetry is shown by the Hartree-Fock method (3-21G basis) to be the predominant conformer of calix[4]arene; the compressed cone of C ₂ symmetry is the major conformer of calix[6]arene. Using quantum chemical methods we calculated hydrogen bond cleavage energies for calix[4]-(ab initio and density functional methods) and calix[6]arene (ab initio), and also for the complex of calix[4]arene with carbon disulfide. These energies along with structural data point to the cooperative effect of hydrogen bonds. The results of these studies provided an explanation to the greater conformational lability of calix[6]arene compared with calix[4]arene molecules. It is also predicted that the nucleophilic substitution reaction involving calix[6]arene in the presence of weak bases and in aprotic solvents, as well as in the gas phase, will occur via diastereomeric transition states.     

New chiral β-diketones based on [2.2]paracyclophane

Two chiral β-diketones, 1,3-bis[(S)-(4-[2.2]paracyclophanyl)]propane-1,3-dione (BPPD) and [1-(S)-(4-[2.2]paracyclophanyl)-3-phenyl]propane-1,3-dione (PPPD), were synthesized by acylation of (S)-4-acetyl[2.2]paracyclophane with methyl esters from the corresponding carboxylic acids. 4-Acetyl[2.2]paracyclophane was synthesized in a quantitative yield by the reaction of [2.2]paracyclophane-4-carboxylic acid with methyllithium.     

Five-membered 2,3-dioxoheterocycles: XCVI. Reactions of 3-aroylpyrrolo[1,2-a]quinoxaline-1,2,4(5h)-triones with substituted 1,3,3-trimethyl-2-azaspiro[4.5]dec-1-enes

3-Aroylpyrrolo[1,2-a]quinoxaline-1,2,4(5H)-triones react with 1,3,3,7,9-pentamethyl-2-azaspiro-[4.5] deca-1,6,9-trien-8-one and 2′,5′,5′-trimethyl-4′,5′-dihydro-4H-spiro[naphthalene-1,3′-pyrrol]-4-one providing 3-aroyl-2-hydroxy-3a-{(3,3,7,9-tetramethyl-8-oxo-2-azaspiro[4.5]deca-1,6,9-trien-1-yl)methyl}pyrrolo[1,2-a-quinoxaline-1,4(3a H,5H)-diones and 3-aroyl-2-hydroxy-3a-{(5′,5′-dimethyl-4-oxo-4′,5′-dihydro-4H-spiro[naphthalene-1,3′-pyrrol]-2′-yl)methyl}pyrrolo[1,2-a]-quinoxaline-1,4(3aH,5H)-diones.     

Synthesis and Complexation properties of N,N’-bis(calix[4]Arenoxyacetyl)Hydrazine Derivative

Heating of p-tert-butylcalix[4]arene bearing acethydrazide moiety at the lower rim in MeCN or PrⁱOH (EtOH) affords the corresponding N,N’-bis(calix[4]arenoxyacetyl)hydrazine derivative. The hydrazinolysis of mono(methoxycarbonylmethoxy)-p-tert-butylcalix[4]-arene in benzene or refluxing biscalixarene hydrazide in benzene in the presence of hydrazine hydrate produces the mixture of 1,2- and 1,3-(N,N’-diacetylhydrazine)-p-tert-butylcalix[4]arenes.     

Reaction of 3,4,4,5-tetrachloro-4H-1,2,6-thiadiazine with benzyltriethylammonium chloride

3,4,4,5-Tetrachloro-4H-1,2,6-thiadiazine was reacted with BnEt₃NCl (10?mol%) to give perchloro-9-thia-1,5,8,10-tetraazaspiro[5.5]undeca-1,4,7,10-tetraene (up to 18% yield), 4,5,6-trichloropyrimidine-2-carbonitrile (up to 44% yield) and four minor side products: 2,7-dichlorothiazolo[5,4-d]pyrimidine-5-carbonitrile, 2-(4-chloro-6H-thiazolo[5,4-c][1,2,6]thia-diazin-6-ylidene)malononitrile, 4,8-dichloropyrrolo[2′,1′:2,3]imidazo[4,5-c][1,2,6]thiadiazine-6,7-dicarbonitrile and 4,7-dichloro-[1,2,6]thiadiazino[3,4-b]thiazolo[5,4-e][1,4]diazepin-9(10H)-one. Single crystal X-ray studies support the structures of the minor products. Tentative rationale for the formation of these minor products and the synthesis of 8-bromo-4-chloropyrrolo[2′,1′:2,3]imidazo[4,5-c][1,2,6]thiadiazine-6,7-dicarbonitrile are presented.     

Revisit to the reaction of [60]fullerene with nitrile ylides generated from imidoyl chlorides and triethylamine

The reaction of [60]fullerene (C₆₀) with nitrile ylides generated from N-benzyl-4-nitrobenzimidoyl chloride/N-(4-chlorobenzyl)-4-nitrobenzimidoyl chloride and triethylamine gave only isomeric monoadducts of C₆₀ with [6,6]-closed structure. No [5,6]-open adduct of C₆₀ could be identified from these reactions. The previously reported [5,6]-open product of C₆₀ should be reassigned as a [6,6]-closed product.     

Pentakis-thiacalix[4]Arenes with Nitrile Fragments: Receptor Properties toward Cations of Some s-and d-metals and Self-assembly of Nanoscale Aggregates

Pentakis-thiacalix[4]arenes containing thiacalix[4]arene fragments in cone, partial cone and 1,3-alternate conformations as their central core have been obtained. Their interaction with cations of s- and d-metals gives supramolecular assemblies whose composition depends on the conformation of pentakis-thiacalix[4]arenes and the nature of the ‘guests’.     

Synthesis of two new p-tert-butylcalix[4]arene β-ketoimin derivatives for extraction of dichromate anion

In this study the selective derivatization of p-tert-butylcalix[4]arene was carried out and two new p-tert-butylcalix[4]arene β-ketoimin, 5,11,17,23-tetra-tert-butyl-25,27-bis-3-methyl-[(β-ketoimine)-ethoxy]-26,28-dihydroxycalix[4]arene (4), and 5,11,17,23-tetra-tert-butyl-25,27-bis-3-chloro-[(β-ketoimine)-ethoxy]-26,28-dihydroxycalix[4]arene (5) have been synthesized. In the synthesis, the lower rim of p-tert-butylcalix[4]arene was modified in order to acquire binding site for the recognition of dichromate anion. It was observed that these ionophores 4 and 5 showed high affinity towards dichromate anion. The protonated Schiff-base forms of the receptors were effective for transferring the HCr₂O₇ ^? anion from aqueous phase to a dichloromethane phase.     

Annulation reaction of methyl 2-(benzo[b][1,4]thiazin-3-ylidene)acetate with β-nitrostyrenes and 3-nitrochromenes

The acid catalyzed domino reaction of β-nitrostyrenes with methyl 2-(benzo[b][1,4]thiazin-3-ylidene)acetate, which were previously prepared from the cyclization of 2-aminobenzenethiol and methyl 4-chloroacetoacetate, resulted in 2-arylbenzo[b]pyrrolo[1,2-d][1,4]thiazine-3-carboxylates in high yields. Under same reaction conditions, the similar reaction with 3-nitrochromenes afforded corresponding benzo[b]chromeno[4′,3':4,5]pyrrolo[1,2-d][1,4]thiazine derivatives in good yields.     

Cyclization of substituted 3,4-diaminopyridines into 1H-[1,2,3]triazolo[4,5-c]pyridine 2-oxide derivatives during the nitration process

The nitration of pyridine-3,4-diamine, its N,N′-diacetyl derivative, and N ⁴-alkylpyridine-3,4-diamines with excess nitric acid in concentrated sulfuric acid at 60°C was accompanied by cyclization with formation of the corresponding 1-substituted 4-nitro-1H-[1,2,3]triazolo[4,5-c]pyridine 2-oxides. 4-Chloro-1H-[1,2,3]triazolo[4,5-c]pyridine 2-oxide derivatives were obtained under analogous conditions from 2-chloropyridine-3,4-diamine, its N,N′-diacetyl derivative, and 2-chloro-N ⁴-methylpyridine-3,4-diamine. The nitration of these compounds at 80–90°C gave 4-chloro-7-nitro-1H-[1,2,3]triazolo[4,5-c]pyridine 2-oxides.