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The strong photoluminescence properties of europium complexes with organic ligands attracted the attention of many researchers and found a wide range of uses in medical, industrial and biological fields. In this article, four new Tetrakis europium complexes 3a, 3b, 3c and 3d have been prepared using 1-phenyl-4,4,4-trifluoro-1,3-butenedionato ligand and pyridinium, bipyridinium, piperazinium and piperidinium counter cations. These complexes have been characterized by negative FAB-mass. The crystal structures of 3a, 3b, 3c and 3d were determined by single crystal X-ray diffraction analysis. The complex 3a crystallized in monoclinic form, space group P21/n with four molecules in the unit cell. The complex 3b crystallized in monoclinic form, space group P2/n with two complex molecules in the unit cell. The complex 3c crystallized in monoclinic form, space group C2/c with sixteen molecules in the unit cell. The complex 3d crystallized in monoclinic form, space group P21/n with four complex molecules in the unit cell. The complex 3a has 1,2-alternative structure, 3b has 1,3-alternative structure, 3c has cone like structure and 3d has partial cone like structure. The photoluminescence properties of these complexes have been evaluated. Strong red emissions were observed in all four complexes due to 5D0 → 7F2 transition of Europium (III) ions under UV excitation. Four β-diketone ligands acted as strong antenna ligands and transferred the absorbed energy to europium (III) ion effectively; consequently strong red luminescence was observed.

Viologens (N,N'-dimethyl-4,4-bipyridinium) are advanced functional materials, found important applications in electrochromic devices, molecular machines, organic batteries, and carbohydrate oxidation catalysts in alkaline fuel. In this article, we investigated the design, synthesis and photophysical properties of N,N'-dimethyl-2,5-Bis(pyridinium)oxadiazole 4 and its precursor 2,5- Bis(pyridine)oxadiazole 2. The crystal structure and photophysical properties of viologen 4 and precursor 2 have been determined. The viologen molecule 4 crystallized in monoclinic form, space group P21/n with four molecules in unit cell. Precursor molecule 2 also crystalized in monoclinic form, space group C2/c with four molecules in unit cell. From X-rd data, we found three cations in the molecular structure of viologen molecule 4, which is unusual in viologens. In the three-dimensional molecular packing diagram of molecule 4, the three cations and iodate anions are stabilized by C···C, C···I, N···I, N···H, H···I, N—H···I and C—H···I. The dihedral angle between planes having oxadiazole and two benzene rings are 5° and 8°, suggesting the molecule 4 is a slightly strained one. The molecular structure of precursor molecule 2 stabilized by C···C and N···H short contacts between the molecules. The molecule 4 displayed strong absorbance at 315 nm and emissions between 390 - 410 nm.

We studied on the geometric and electronic structures of a newly synthesized compound, 3-(tert-butyl)dinaphtho[1,2-b;1′,2′-d]furan-12,13-dione (1), having a twisted molecular structure at an o-quinone region in a crystal. The density functional theory (DFT) has been applied to investigate the geometric and electronic structures using the model compound (1H), where a tertiary butyl group of the compound 1 is replaced by a hydrogen atom. The optimized geometry for the model dimer of 1H represented well the twisted molecular structure of 1. The time-dependent DFT method explained the observed optical properties of 1 in a solution and a powdery solid. The DFT calculations also gave a good estimation of the ionization potential and the electron affinity of 1H, explaining a similarity in reduction and a difference in oxidation between 1H and o-benzoquinone. This similarity in the electron affinity was confirmed by measuring a reduction potential of the compound 1 with cyclic voltammetry.

Two π-conjugated materials (3a, 3b) possessing –CF3 and -CN were prepared by Knoevenagel condensation by reacting benzene 1,3,5-tricarboxaldehyde and 4-(trifluoromethyl) phenyl acetonitrile, 3,5-bis(trifluoromethyl) phenyl acetonitrile in the presence of sodium ethoxide. The proposed structures of 3a, 3b were elucidated by 1H NMR and Elemental analysis. To study the structure-property relationship, molecular structures of 3a and 3b were determined by X-ray diffraction analysis. In the crystal, molecules are linked by C_H⋯F, C⋯C and F⋯F short contacts, forming a layer like three dimensional networks. From X-ray diffraction analysis it was observed that molecule 3a has better planarity than molecule 3b suggested by angles between the planes of molecules. The molecules 3a and 3b displayed strong absorption maximum at 319 nm corresponding to the π→π* transitions within the whole conjugated molecules and emissions in the visible region at 373–475 nm. The shape and intensity of absorption and emission spectra of 3a, 3b almost identical. Further, we found that molecule 3b (M.p. 251–252 °C) has relatively higher melting point than molecule 3a (M.p. 231–232 °C). Molecules 3a and 3b have emissions close to blue light, may serve as model materials for new OLED applications.

Three new thiophene condensed fluorescent pyrene derivatives have been synthesized by a two-step process, via. Wittig reaction followed by iodine promoted photocyclization. These molecules have been characterized by 1 H NMR and EI-MS. Further, the molecular structures of 4a, 4b and 4c has been confirmed by single crystal X-ray diffraction analysis. The protons located in the fjord and cove-regions of molecules 4b and 4c showed downfield shifts of the protons. Molecule 4a crystallized under monoclinic system with space group P 2 1 / c , molecule 4b crystallized under monoclinic system with space group C 2/ c and the molecule 4c crystalized under triclinic system with space group P -1. Molecules 4a , 4b and 4c showed strong absorption maxima wavelengths at 305, 358 and 330 nm, respectively. The molar extinctinction coefficients ( e ) of the compounds 4a , 4b and 4c indicated molecule 4c has better ability to absorb UV light, molecule 4b has better fluorescence intensity than molecule 4a and 4c .

Three new π-conjugated hetero aromatic materials consisting of pyridine 3a, furan 3b, and thiophene 3c have been synthesized by Knoevenagel condensation reaction. These molecules have been characterized by 1H NMR, EI-MS and single crystal X-ray diffraction analysis. Molecule 3a crystallized under monoclinic system with space group C2/c, molecule 3b crystallized under triclinic system with space group P-1 and the molecule 3c crystalized under triclinic system with space group P-1. The optoelectronic properties of these compounds have been studied.Molecules 3a, 3b and 3c showed strong absorption maxima wavelengths at 300, 419 and 418 nm, respectively. The molar extinction coefficients (e) of the compounds 3a, 3b and 3c suggested that molecule 3b has better ability to absorb UV light; molecule 3a has better fluorescence intensity than molecule 3b and 3c. Low energy gaps of HOMO and LUMO energy levels of these compounds suggests that these compounds may be a promising new class of lead compounds for developing high performance semiconductor materials. Compounds 3a, 3b and 3c has emissions near to blue light, a slight modification of the structures by extending conjugation may find important applications in optoelectronic devices as blue light emitters in organic light-emitting devices for the development of new generation organic semiconducting materials.

Two s-shaped fluorinated isomeric polyaromatic dibenzo[c,l]chrysene derivatives have been synthesized by a two step process using the Wittig, Heck and iodine promoted cyclization reactions. These cyclized compounds were characterized by 1 H NMR and EI-MS. Further, absolute configurations of isomeric 4a and 4b were determined by X-ray diffraction analysis. Compound 4a crystallized under monoclinic system with space group P 2 1 / c and compound 4b crystallized under monoclinic system with space group Cc . They have good solubility in common organic solvents such as dichloromethane, chloroform and THF. Photophysical properties of 4a and 4b were evaluated by using UV–Visible and Fluorescence spectrophotometer. Compounds 4a and 4b showed strong absorption maximum wavelength at 317 nm. The emission spectra of 4a and 4b displayed sharp peaks in the visible region from 417 to 441 nm. The shape of the UV–Visible and Fluorescence spectra of 4a and 4b looks almost identical. But compound 4a exhibited better fluorescence intensity than compound 4b. This difference may be due to the difference in the configuration of compounds 4a and 4b .

Two kinds of glutamaic acid-based coumarin derivatives show a quite different trend against gelation in organic solvents in terms of inter- or intramolecular hydrogen bonds involved. It has been found out that addition of the valinate structure into the coumarine derivative could improve its gelation ability.

Organogelator candidates which consist of the ferrocene unit have been prepared. It has been suggested that two amino acid residues in the structure are necessary to form a stable organogel. Addition of an oxidizing agent such as NaClO induces the collapse of the gel, and reproduction of the gel was observed by addition of a reducing agent such as glutathione. It has been found out that the on-off switching of gel formation can be achieved by red-ox reaction.

Treatment of 1,3-diphenyl-1,3-propanedione 1a with europium (III) chloride in the presence of piperidine results in the halide ligands exchange giving newly piperidinium tetrakis (1,3-diphenyl-1,3-propanedionato)europate(III) complex 2a. The complex was characterized by 1H-NMR, positive FAB-mass, and Elemental Analysis. The exact molecular structure of 2a was determined by single crystal X-ray diffraction with the monoclinic space group Cc (centrosymmetric, No.13). The large cavity sizes of the complex 2a facilitated the inclusion of water and benzene solvate molecules. The other two different crystals 2b, 2c having two water molecules and one benzene moleculewere obtained by the crystallization in different solvents and the exact molecular structures were determined by single crystal X-ray diffraction analysis with space groups P21/n (centrosymmetric, No.14), and P21/n (centrosymmetric, No.14), respectively. The eight coordinate structures of the complexes in the three crystals were slightly different due to the crystal packing and the existence of the solvent molecule(s). The photoluminescence studies indicated that four β-diketone ligands acted as strong antenna ligands and transferred the absorbed energy to europium (III) ion, consequently red luminescence was observed. These strong emissions wereattributed to the 5D0 → 7F2 transition of Europium (III) ions under UV excitation. The photoluminescence spectrum of the three crystals was almost same in solid as well as in solution.

New and simple polyaromatic compounds containing two thiophene rings were prepared via photo-cyclization and their structural and photophysical properties were evaluated via 1 H NMR spectroscopy and X-ray crystallographic analysis. On the basis of X-ray analysis, it was determined that the molecular structure of the compound was highly strained and that they contain two hetero [4] helicene moieties. The compounds were investigated as active layer in p-type organic field-effect transistors ( p -OFET) in top contact type devices. Notably, the compound containing two thiophene components exhibited very stable p-type semiconducting behavior in moist air.

An efficient, mild and multicomponent synthesis of novel heterocyclic compounds possessing the pyrrolo[2,3-c]pyridone backbone was achieved using the Ugi four-component reaction and post-condensation of the Ugi adduct. This method offers many advantages, such as an easy handling procedure, atom economy, short reaction time, and a huge molecular library that can be synthesized by changing the substituents on the four independent starting materials. This methodology was also successfully employed for the electron deficient anilines and phenyl glyoxylic acids having CF3 group. All the products were characterized using NMR (1H and 13C) spectroscopy and FAB mass spectrometry. Product 6g was further characterized by X-ray diffraction analysis.

Two novel dithia[3.3]metacyclophanes substituted with ethynyl groups were synthesized as small-sized metacyclophanes from the corresponding brominated dithia-metacyclophanes via C-C bond formation reaction. These compounds were characterized by using 1H NMR, mass spectrometry and elemental analyses. The exact structures were determined by using X-ray diffraction analyses. X-ray diffraction analysis results revealed that these compounds have anti conformations because of existence of intermolecular π-π interaction and some short contacts in the crystal. The long wavelength fluorescence was observed for one of the compound having a pyrene moiety in solid state because of the existence of the intermolecular π-π interaction between two pyrene units.

Efficient and facile synthesis of 3-furyl coumarin derivatives have been achieved by reaction of 4-chloro-3-formylcoumarin, secondary amines, dialkyl acetylenedicarboxylates and diversely substituted isocyanides using four component, one-pot reaction. All the products were isolated as yellow color fluorescent solids by column chromatography in quantitative yield and characterized with 1H NMR, 13C NMR, IR and FAB mass.

The title compound 4’,9’,4”,9”-tetra-tert-butyl-1’,6’,1”,6”-tetramethoxy-2,5-dithia[3.3] metabiphenylophane was synthesized as a calixarene like large-sized metacyclophane from the corresponding 3,3’-bis(chloromethyl)-5,5’-bis(1,1-dimethylethyl)-2,2’-dimethoxy-1,1’-biphenyl and 3,3’-bis (mercaptomethyl)-5,5’-bis(1,1-dimethylethyl)-2,2’-dimethoxy-1,1’-biphenyl via an intermolecular condensation reaction. The compound was characterized using 1H NMR spectroscopy and mass spectrometry. Its exact conformational structure was determined via single crystal X-ray diffraction analysis. The compound has quite strained 1,2-alternate like structure because of its two high dihedral angled and rigid biphenyl parts in the crystal. The crystal includes the two isomers as two different 1,2-alternate like conformers, and the ratio of the two isomers is 78:22.

Two novel thiaheterohelicene derivatives were synthesized from the corresponding 2,2'-(2,6-naphthalenediyl-di-2,1-ethenediyl) bis-thiophene and its dimethyl substituted analogue 2,2'-(2,6-naphthalenediyldi-2,1-ethenediyl) bis-2’’-methylthiophene using oxidative photo cyclization reaction. The compounds were characterized by 1H NMR, electron impact-mass spectrometry, elemental analyses, and the absolute molecular structures were determined by single crystal X-ray diffraction analysis. They crystallized under monoclinic system with space group P21/n for the unsubstituted compound and P21/c for the methyl substituted compound, respectively. The dihedral angle between the terminal thiophene ring and the molecular center was observed to be 20.82? for the unsubstituted compound and 14.27? for the methyl substituted compound, respectively. Furthermore, molecules oriented as herringbone structures by intermolecular π-π stacking in the crystals. The relative study of the actual arrangement of these molecules has been carried out using X-ray diffraction analysis. The two molecules have different crystal packing. The molecule 3b has herring bone like arrangement due to the substituent bulkiness and weak CH-π interaction. On the other hand, the molecular packing of molecule 3a is not herringbone probably due to the multiple weak intermolecular CH-S short contacts between columns consisting of stacked molecules.

Metacyclophanes having the urea units in their bridge have been prepared. It has been found out that some of them afford stable organogels in some solvents. It was also observed that addition of fluoride anion broke DMSO gel, and then this gel was formed again by addition of MeOH.

Novel di-tert-butylated polycyclic aromatic hydrocarbons (PAHs) with [4] helicene components were prepared through an oxidative photocyclisation reaction. The structural properties of the PAHs were evaluated with 1H NMR and X-ray crystallography. It was detected that the PAHs have highly twisted π-conjugated systems and a deep fjord region. Although they are not planar, these PAHs can readily form dimers in solutions and undergo staggered one-dimensional array columnar crystal packing by intermolecular π–π interactions.

Diethyl malonate derivatives were used to synthesize racemic 2-amino-5-hexenoic acid. These racemic 2-amino-5-hexenoic acid (homoallylyglycine) derivatives were efficiently resolved aided by α-chymotrypsin or L-acylase, giving rise to L- and D-enantiomers. These isolated enantiomerically pure amino acids with tert-butoxycarbonyl (Boc) protection were oxidised with 3-chloroperbenzoic acid. The oxidation gave rise to inseparable diastereomeric epoxides due to a newly generated chiral center at the C5 carbon. The isolation of one of the diastereomeric epoxides was possible by selectively converting the remaining diastereomer into a dihydroxyl compound catalysed by Jacobsen's hydrolytic kinetic resolution (HKR). The isolated epoxide was regioselectively attacked by LiBr to give vicinal halohydrin, with bromide attacking the terminal C6 carbon. Boc deprotection of the halohydrin led to intramolecular cyclization by attack of free amine at the C6 carbon, generating a single isomer of 5-hydroxypipecolic acid which was effortlessly recovered in good yield after re-protection of the amine with the Boc group. Similarly the dihydroxyl compound isolated earlier was converted to a halohydrin with iodine at the C6 carbon. This was feasible by efficient regioselective mono-tosylation with catalytic Bu2SnO followed by iodine substitution. This was utilized to synthesize the 5-hydroxypipecolic acid derivative in the same described sequence consisting of Boc removal by acid treatment, cyclization, reprotection and purification. Finally the same sequence was repeated with the D-isomer and two diastereomers were isolated.

Two s-shaped polyaromatic dibenzo[c,l]chrysene derivatives have been synthesized by a two-step process, via. The Wittig reaction, followed by iodine, promoted photocyclization. These molecules have been characterized by 1H NMR, FAB-MS, and elemental analysis. Further, the molecular structures of 4a and 4b have been confirmed by single crystal X-ray diffraction analysis. The protons located in the cove-regions of molecules 4a and 4b showed downfield shifts of the protons. Molecule 4a crystallized under the monoclinic system with space group C2/c, and the molecule 4b crystallized under the monoclinic system with space group P21/n. Molecules 4a and 4b showed strong absorption maxima wavelengths at 310 nm and 324 nm, respectively. The molar extinctinction coefficients (ε) of the compounds 4a and 4b indicated that molecule 4b has a better ability to absorb UV light than molecule 4a. The emission spectra of the molecules 4a and 4b displayed peaks in the region 429–456 nm. The shape of the UV-Visible and Fluorescence spectra of the molecules 4a and 4b look almost identical. However, molecule 4b exhibited better fluorescence intensity than molecule 4a. This may be due to the difference in the substituents of molecules 4a and 4b.

The reaction of 1-trifluoromethyl-3-(1′-pyreno)-1,3-propanedione with lanthanum(III) trichloride in the presence of pyridine leads to halide ligand exchange, yielding a novel pyridinium tetrakis{1-trifluoromethyl-3-(1′-pyreno)-1,3-propanedionato}lanthanate(III) complex with four polycyclic aromatic hydrocarbon moieties. This reaction easily proceeds under mild conditions (25°C, 24 h) producing the complex in a 90% isolated yield. The complex was characterized by infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, and positive fast atom bombardment mass spectrometry, and its precise structure was determined by single crystal X-ray diffraction. Ultraviolet-visible spectroscopy, fluorescence spectroscopy, and X-ray analysis demonstrated that the four pyrene moieties were independently oriented.

The exact molecular structure and the crystal packing of the n-type semiconducting material 3′,3′-(1,4-phenylene)bis{2′-(4′′-trifluoromethyl)phenyl}acrylonitrile was determined by a single crystal X-ray diffraction with twin treatment technique. The air-stable product was crystallized from dichloromethane-hexane mixed solution. The solid-state structure is the example of a typical π-π stacking with side intermolecular CN–H short contact networks.

The compound tert-butyl 3-oxo-2-oxa-5-azabicyclo[2.2.2]octane-5-carboxylate was synthesized as a cyclic amino acid ester from the corresponding ethyl 2-amino-4-(2-oxiranyl)butanoate HCl salt via an intramolecular lactonization reaction and was characterized by using 1H NMR spectroscopy and high-resolution mass spectrometry. The product was then recrystallized from dichloromethane/diethyl ether and its structure was determined via single crystal X-ray diffraction analysis. The crystal was found to be of the monoclinic space group P21/c (no. 14) with a = 10.217(2) Å, b = 11.676(3) Å, c = 10.273(3) Å, β = 114.186(13)°, and Dcalc = 1.350 g/cm3 at 123 K. The compound has bicyclo[2.2.2]octane structure including a lactone moiety and a piperidine ring, and the two diastereomers of the molecules are present in a 1 : 1 ratio in the crystal.

A long-term air-stable n-type organic semiconductor, 2,5-difluoro-1,4-phenylene-bis{2-[4-(trifluoromethyl)phenyl]acrylonitrile}, was synthesized by a high-yield simple procedure of Knoevenagel condensation with aldehyde and acetonitrile derivatives. A fabricated organic thin-film transistor (OTFT) using this compound exhibited good n-channel OTFT properties with a high electron mobility of 0.17 cm(2) V(-1) s(-1) and an on/off current ratio of 10(6) under both vacuum and ambient air operation. After storage in ambient air for 1 year, a stored n-channel OTFT still shows good n-channel OTFT performance with little degradation in ambient air operation.

A new collaborative research project for systematic treatments of radioactive liquid wastes containing various reagents generating in nuclear facilities was started from 2018 initiated by Japan Atomic Energy Agency. The project was named as STRAD (Systematic Treatments of RAdioactive liquid wastes for Decommissioning) project. Tentative targets to be studied under the project are aqueous and organic liquid wastes which have been generated by experiments and analyses in a reprocessing experimental laboratory of JAEA. Currently fundamental studies for treatments of the liquid wastes with complicated compositions are underway. In the STRAD project, process flow for treatment of ammonium ion involved in aqueous waste was designed though the inactive experiments, and decomposition of ammonium ion using catalysis will be carried out soon. Adsorbents for recovery of U and Pu from spent solvent were also developed. Demonstration experiments on genuine spent solvent is under planning.

Dithia[3.3]metacyclophanes which consist of the pyridine unit connecting to the different positions of the parent cyclophane skeleton have been prepared. Conformational change has been observed for the cyclophane having a 4-substituted pyridine unit by binding to the porphyrin. In contrast the porphyrin binding has no influence on conformational behavior of the cyclophane having a 3-substituted pyridine unit.

The complete molecule of the title compound, C36H30S4{common name: 1,4-[4-(9,17-dithia[3.3]metacyclophane)]-1,3-butadiyne}, is generated by a crystallographic inversion centre at the mid-point of the central C—C bond [1.367 (5) Å]. Both cyclophane units exist incisoidpseudo-boat–chair chair–boat conformations. In the crystal, the packing is controlled by van der Waals interactions.

Efficient and facile synthesis of 3-furyl coumarin derivatives have been achieved by reaction of 4-chloro-3-formylcoumarin, secondary amines, dialkyl acetylenedicarboxylates and diversely substituted isocyanides using four component, one-pot reaction. All the products were isolated as yellow color fluorescent solids by column chromatography in quantitative yield and characterized with 1H NMR, 13C NMR, IR and FAB mass.

In the title compound, C13H19NO3, the hexyl chain has en extended conformation and its mean plane is inclined to the benzene ring by 3.29 (10)°. There is a short O—H...O contact in the molecule involving the adjacent hydroxy groups. In the crystal, molecules are linkedviaO—H...O and N—H...O hydrogen bonds, forming slabs parallel to (001). Within the slabs, there are also C—H...O hydrogen bonds and C—H...π interactions present.

Ultraviolet photoelectron spectroscopy (UPS) has been applied to investigate the valence electronic structures of the double-decker type phthalocyanine compound, bis(phthalocyaninato)tin(IV) (SnPc2). The binding energies of spectral features were precisely determined and compared to those of tin(II) and lanthanide compounds. Two peaks were observed at 5.11 and 6.04 eV in the lower binding energy region, which corresponded to the molecular orbitals generated by the anti-bonding and bonding interactions between the orbitals of the two phthalocyanine rings, respectively. It is worthy to note that the ionization threshold of SnPc2 is remarkably small as compared to other phthalocyanine compounds, implying ease of oxidation. Actually, oxidized forms of SnPc2 were easily obtained by both chemical and electrochemical reactions, and their electronic structures were discussed in comparison with that of SnPc2 and with the recent results of the density functional theory calculations.

Two types of dithia[3.3]metacyclophanes having cofacial bisporphyrins were prepared. The flexible cyclophane having C2 methylene units as the spacer exhibits the large stability constant (108M-1) for binding of 1,4-diazabicyclo[2.2.2]octane (DABCO). Similar large affinity for DABCO is also observed for the rigid cyclophane having C10 methylene units.

In the title compound, C25H20O12, commonly known as pentaacetylated quercetin, the benzene ring and one of its methoxy substituent groups is disordered (site occupancy ratio 0.523:0.427), with a dihedral angle between the major-disorder component and the benzene ring of the benzopyranone moiety of 10.8 (6)°. In the crystal, C—H...O hydrogen-bonding interactions give chains which extend alongb.

An efficient and facile method for the synthesis of novel spiro[indole-2,2′-pyrroles] from N-methyl-3-isatin imines, t-butyl isocyanide, and dialkyl acetylenedicarboxylate has been achieved by [3 + 2] cyclo addition reaction. All the products were purified by column chromatography as yellow solids and confirmed with 1H NMR, 13C NMR, fast atom bombardment, mass, and infrared. Compound 11 was further confirmed with x-ray analysis.

The title compound, C16H16O2S2·C4H8O2, is a cyclophane derivative, which was crystallized from an ethylacetate/methanol solvent system. The metacyclophane moiety exists with the benzene rings in thesynorientation, and with a pseudo chair–chair conformation for the dithia 12-membered ring. Both hydroxy groups are positioned on same side of this ring. In the crystal, the cyclophane and the lattice solvent are linked by O—H...O hydrogen bonds.

In the title compound, C17H18ClNO5, which was synthesized by reacting 4-chloro-3-formylcoumarin, acetic acid andtert-butyl isocyanide, the acetamido side chain is convoluted with ring-to-side chain C—C—C—C, C—C—C—N and C—C—N—C torsion angles of −123.30 (14), −135.73 (12) and 176.10 (12)°, respectively. In the crystal, N—H...O and weak C—H...O hydrogen bonds are present, which together with π–π coumarin-ring interactions [ring centroid separations = 3.4582 (8) and 3.6421 (9) Å], give rise to a layered structure lying parallel to (001).

In the title compound, C11H17NO4, commonly known asN-tert-butoxycarbonyl-5-hydroxy-D-pipecolic acid lactone, the absolute configuration is (1R,4R) due to the enantiomeric purity of the starting material which remains unchanged during the course of the reaction. In the crystal there no intermolecular hydrogen bonds.

Formation of organogels from europium(III) complexes consisting of ligands having an amide or a urea unit has been achieved; the organogels are characterized by strong red-emissions.

Various substituents have been introduced into the inner position of the dithia[3.3]metabenzenopyridinophanes (MPPs) and their conformational are evaluated by variable temperature 1H NMR spectral measurements, IR measurements, computer calculation and X-ray structural analyses.