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Presented work compares optical and chemical properties of As30S70, As35S65 and As40S60 amorphous chalcogenide thin films deposited by thermal evaporation and by spin-coating. Structural and compositional differences given by the chosen deposition technique and post deposition treatment were revealed by Raman spectroscopy and EDS. Applicability of studied thin films in electron beam lithography was investigated using both monoamine and diamine based developers. Thermally evaporated thin films exhibited negative etching contrary to the spin-coated films which showed positive etching. Studied thin films proved to be suitable positive and negative photoresists for both grey-scale and step-like lithography.

Spectroscopic imaging ellipsometry was used to study 50 μm × 50 μm squares recorded into glassy As35S65 thin film by electron beam with different exposure doses. Optical constants (refractive index n and extinction coefficient k) of electron exposed areas were determined from imaging ellipsometric data recorded over a spectral range 390–800 nm. Complex dielectric permittivity of each of electron exposed square (glassy As35S65 with different electron exposure dose) was parametrized by a Tauc-Lorentz oscillator. Gradient optical model with the refractive index changing linearly within the layer thickness was used. Evaluation of parameters of Tauc-Lorentz oscillator revealed decrease of energy bandgap, increase of the refractive index in whole recorded spectra (more pronounced at the top of the film) and increase of extinction coefficient in the part of spectra where the material absorbs with the increasing electron exposure dose used for exposure of the squares. The decrease in local disorder with increasing electron exposure dose is quantified from the short wavelength absorption edge onset using a Mott-Davis model. The dependence of the parameters of Wemple-DiDomenico model for the transparent part of the optical constants spectra on electron exposure dose is shown. Thin film with recorded image was subsequently etched in amine based solution in aprotic solvent. While native film was fully etched off the remaining height of the exposed areas is increasing with the increasing electron exposure dose used. Knowledge of the changes of optical properties and etching rates induced by electron beam of different exposure doses can be used for fabricating of optical elements by high resolution electron beam lithography.

Semiconductor quantum dots (QDs) with stable and wavelength-tunable photoluminescence (PL) are very promising emitters for various photonic and optoelectronic applications. In this paper, we describe a comparison of four synthetic approaches for highly photoluminescent blue-emitting Cd0.15Zn0.85S QDs. (Z)-1-(Octadec-9-enyl)-3-phenylthiourea, initially prepared from phenyl isothiocyanate and oleylamine, was used as the source of sulfur. Environmentally friendly and commercially available N,N′-disubstituted thiourea in combination with well-known methods is a suitable precursor for the highly reproducible synthesis and further large-scale production of ternary Cd0.15Zn0.85S QDs. This study was carried out to examine the mechanism of interaction between disubstituted thiourea and metal carboxylates in one of two tautomeric forms under the influence of oleylamine, which was taken as a base in the synthesis of the QDs by hot-injection and one-pot methods. Chemical and thermal decompositions of the QDs were performed to get information about the amount and composition of organic ligands in their shells. To elucidate the mechanisms of QD formation, the organic products were studied by NMR. Optical studies showed that the prepared nanomaterials exhibit narrow emission peaks with a full width half maximum (FWHM) of around 19–33 nm and a very small size of nanocrystals (1.59–3.53 nm).

The paper presents the synthesis of some natural diterpenoids of ent-kauranic structure, starting from ent-kaur-16-en-19-oic acid, a natural diterpenoid readily available from the dried wastes of sunflower (Helianthus annuus L.). The reported ent-16α,17-dihydroxykauran-19-oic, ent-16α-hydroxy-17-acetoxykauran-19-oic and ent-16α,17-diacetoxykauran-19-oic acids have been previously isolated from different plant sources and showed diverse biological activities, including anti-HIV, anti-cancer and anti-Alzheimer properties. Their chemical synthesis has not been disclosed so far. Additional cytotoxicity studies of the obtained compounds revealed a remarkable cell proliferative effect of parent ent-kaur-16-en-19-oic acid and two of its synthetic derivatives, which is in line with recent pioneering studies in this area.

The first biomimetic synthesis of methyl (8 S ,9 R ,13 R ,14 R )-4,4,8,9,13-pentamethyl-20(10 → 9)-abeo- ent -isocopal-5(10),11(12)-dien-15-oate—a diterpenoid with the ent -verrucosin A/B skeleton has been performed by electrophilic isomerization of methyl 12α-hydroxy- ent -isocopal-13(16)-en-15-oate. The structure and stereochemistry of the synthesized compound have been established on the basis of spectroscopic data.

Synthesis of polyfunctional triterpene derivative [8(27),13E,17E,21E]-15-phenylsulfonyl-16-oxobicyclofarnesylfarnesol benzyl ether (8) from commercially available monoterpene geraniol and diterpene manool has been accomplished in 73% yield and its chemical transformation in superacid medium has been investigated. An unexpected rearrangement of 8 occurred, which involved methyl migration in the bicyclic fragment and total inhibition of the lateral polienic chain. A new bicyclic triterpene product [5(10),13E,17E,21E]-15-phenylsulfonyl- 16-oxo-30(10→9)-abeo-bicyclofarnesylfarnesol benzyl ether (9), with rearranged new carbon skeleton has been obtained. Its bicyclic moiety is analogous to this of a natural triterpene neopolypodatetraene.

The content of known tetra- and pentacyclic diterpenoids in extracts of sunfl ower (Helianthus annuus L.) dry wastes has been studied using different solvents for extraction. It was established that the largest extracted quantity of ent-kaur-16-en-19-oic acid is obtained when ethanol and diethyl ether are used for extraction of the plant material.

An efficient one step, retro-biomimetic procedure for the synthesis of natural products having the atisane structure is described (Scheme 2), natural products which are components of medicinal plants and possess relevant biological activity. Their structures were confirmed by chemical transformations and spectral data. The starting materials were the known ent-kaur-16-en-19-oic acid (1) and ent-trachyloban19-oic acid (2), diterpenoids readily available from the waste of sunflower.

We present the study of volatile amine-based single or multi-component solvent formulations and their influence on As30Se70 chalcogenide glass solubility and dissolution mechanism. The source As30Se70 bulk glass was dissolved in various amine based solvents, and solutions of quantitatively dissolved bulk glass were used for thin films deposition by the spin-coating technique. The methanol – n-propylamine solvent mixture proved to be suitable for preparation of thin films in specular optical quality, low surface roughness and targeted composition. The post-deposition thermal treatment has a high impact on the thickness, optical properties and structure of the studied thin films. The content of the organic residuals was also significantly reduced.

A relatively simple method for isolation of the mixture of ent-kaur-16-en-19-oic (1) and ent-trachiloban-19-oic (2) acids from dry waste of sunflower processing has been elaborated, and it has been shown that the waste can serve as an accessible source of ent-kauranic and ent-trachilobanic diterpenoids.

A review of diterpenoid cyclization initiated by electrophilic reagents is provided. Conventional protonic and Lewis acids are examined along with superacids as initiators of cyclization cascade. An emphasis is placed on the use of cyclization reactions as a tool for the synthesis of compounds with potential practical utility. The review contains 74 references.

An efficient retro-biomimetic procedure for the synthesis of two natural products having atisanic and beyeranic structure is reported. The readily available ent-kaurenoic acid is used as the substrate, which provides under superacidic treatment a mixture of natural ent-beyer-15-en-19-oic and ent-atis-16-en-19-oic acids. These compounds have been reported as components of medicinal plants and possess relevant biological activity. Their structure was confirmed on the basis of chemical transformations and spectral data.

The known diterpenic ester – 15α-angeloyl-ent-kaur-16-en-19-oic (angeloylgrandifl oric) acid has been isolated from the dry wastes of Helianthus annuus L. The synthesis of 15α-hydroxy- and 15-oxo-ent-kaur-16-en-19- oic acids starting from ent-kaur-16-en-19-oic acid has been performed.

The biomimetic synthesis of sacculatane-type epimeric compounds 14a and 14b is reported. The key synthetic step is the low-temperature superacidic cyclization of (all-E)-omega-acetoxygeranylgeraniol 12 obtained in nine steps from geranyllinalool (13). The 19-acetoxysacculata-7,17-dien-11-ol (14a) could be an important and convenient starting compound for the synthesis of other sacculatane diterpenoids.

Methyl (2Z,6Z,10E,14E)- (3) and methyl (2E,6Z,10E,14E)-geranylfarnesoate (4) were prepared, and then individually cyclized in the presence of the superacid FSO3H. In the case of substrate 3, the scalaranic ester 9 (26%) and the cheilanthanic ester 10 (39%) were isolated. Under the same conditions, substrate 4 afforded a mixture of the corresponding stereoisomers 11 (25%) and 12 (63%). The observed product selectivity supports that the internal, (6Z)-configured CC bond in these and other biologically relevant substrates plays an essential role in the cyclization process.