**3. Chalcogen bonds**

are utilized for some purposes according to the new properties and attributes of material, as nanoselenium with their high active surface area and catalytic efficiency [1, 2]. The interest for chalcogen materials is growing rapidly, as seen through SCIFinder [3]. Combinations with other elements make the compounds important for metabolism or for various dedications. The investigation on possibilities of chalcogen elements in reaction has been thoroughly discussed from the internal chemical properties of the elements [4]. Availability of pair and lonepair electrons offers so many possibilities of combination, naturally and synthetically. There has also been a description of the stability of organo-chalcogen compounds by intermolecular

Secondary metabolites and study on metabolomics have dominated the area of biology, food, agriculture, and also medicine, as well as pharmacy. One good example, is the chemistry of garlic, in which the sulfur-containing compounds called Allicin dominated the most beneficial properties of garlic as an antioxidant, antimicrobial and antifungal actions [6]. More similar analysis on *Allium* family revealed that mostly sulfur compounds were responsible for the antioxidant and antimicrobial properties [7]. The phytochemical profiles describe the benefits of sulfur-containing compounds to the good bioproperties which have good prospect in the future. Besides sulfur, selenium plays a preponderant role in cellular metabolism and becomes an essential element in enzyme in protecting the body against oxidative damage as well as many other functions [1]. Selenium is needed in life in certain amount; otherwise, it can be toxic, as sometimes it is called by double-edged sword element [8]. This element is also being well investigated by scientists in relation with its bioavailability in the environment [1, 2]. Originally, selenium is present in rocks, water, and soil, and it has some common isotopes too [9], though it naturally occurs in biological cycles in the environment, including the biochemical and food cycles. Selenium is one of the metalloid essential minerals in living things, whereby its deficiency, in soil and crops can cause certain metabolic disease such as the Kashin-Beck disease, commonly prevalent in the Tibetan plateau [10]. In short, the exploration of chalcogen elements contained in natural compounds as minerals is still intensive

worldwide, while a shift toward agricultural use is currently underway [1, 9, 11].

The new materials in combination with metals and ligands with higher specification and sophisticated preparation are in demand due to great contribution for modern technology. Selenium, for example, can be immobilized through reaction to form selenium metal-humic ternary complexes or incorporated in carbohydrates as well [9]. More related to life, thio-compounds cannot be uncounted for since they are all over the synthetically chemicals through the ligands or thiolates as well as selenolates [12]. Synthetic compounds with metals like Fe by chalcogen arsenide [13] or chalcogen containing iron-carbonyl clusters [14] are already done. Chalcogen elements as dopant in silicon layers [15] or as organo-selenium or tellurium cations [16] are also analyzed by spectroscopy methods. Tellurium is a bigger chalcogen element and tends to have isotopic abundance, from which some are stable and some unstable [17].

There are several reports on chalcogen material synthesis with various synthetic and analytical methods, available in the Handbook of Chalcogen Chemistry [3]; however, with the emergence of new and complex compounds, analytical methods development is undoubtedly becoming an endless effort in the field of chalcogen chemistry. How the new materials are

coordination because of their role in chiral induction [5].

10 Chalcogen Chemistry

Most topics on chalcogen compounds and materials are related to real chemical bonding, which are either ionic or covalent bonding in one molecular building. Fewer discussions describe the weak intermolecular forces that bind molecule or macromolecule together for certain purpose. Chalcogen bonds are important in many intermolecular interactions which in turn determine the configuration and designs of bigger biomolecules [51]. This type of bonding can be grouped as dipole–dipole interaction. In the field of biochemistry, it has much impact due to its role in bigger molecular mobility. The chalcogen bonds also form eclipse (*cis*) and staggered (*trans*) configurations, enable chalcogen elements to develop many types of materials for specific application, from real crystals to real amorphous substances.

**5. Methods for chalcogen materials characterization**

the impurities aspect if not related to their main functionalities.

give elemental confirmation [62].

of the whole materials. Proton and (1

Characterization method is the backbone of chalcogen chemistry material description, as it always accompanies the explanation of material properties [54–57]. There are still some divisions in chalcogen material characterization, which includes the analysis for the main material itself and characterization of the impurities. The presence of impurities will decrease the quality to some extent [58, 59]. Notwithstanding, there have been too few reports discussing

Modern Analytical Chemistry Methods for Chalcogen Materials Analysis and Characterization

http://dx.doi.org/10.5772/intechopen.77989

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Basic spectroscopy methods, especially X-ray methods, are the main tool for material characterization, including chalcogen materials. The methods are based on incoming X-ray beam that undergoes some natural phenomena like absorption, emission, fluorescence, and diffraction, then scattering with many possibilities to explore the chemical composition and properties of the sample. The crystallinity of materials can be derived from the X-ray diffraction patterns and the crystal database from instrument companies. In this case, the X-ray penetrates through the materials, and a number of particles can be expected to be oriented in such a way as to fulfill the Bragg's law. Almost all crystalline compounds analysis rely on XRD spectra, such as analysis of metal complexes of metal-thiourea and metal phenyl-thiourea [60, 61] after several steps of synthesis, to determine the coordination sphere on the metal Zn(II), Co(II) and Cu(II) and the possible crystal structures. More study of the spectra confirmed the shape of crystalline compounds together with UV-Visible and infrared as well as magnetic susceptibility measurement. In other synthesis the X-ray spectra were used to calculate reactive tendency as well as shape of molecules [23–25] besides characterization. Another X-ray technique is the energy dispersive analysis by X-rays (EDX) which intensity is proportional to the amount of the elements. The method is commonly combined with scanning electron microscopy (SEM) to get pre-experimental data, before the variables are given [22, 24, 26] or to characterize and

Nuclear magnetic resonance for solid sample can be powerful to characterize chalcogen materials. It is based on the impact of radiofrequency irradiation on specific nuclei in certain field strength of the magnet (FT-NMR), causing the nuclei to spin resulting in resonance frequency which is an indication of the atom (e.g., 77Se and 125Te) [28]. NMR for chemist such as 1

13C NMR is usually the most important method for chemical structure elucidation. However, material scientists need solid-state NMR with its magic angle spinning (MAS). Moreover, when other nuclei of resonance are used, one must swing the magnetic field according to selected NMR active probe nuclei, such as 77Se and 125Te NMR [28, 29] to describe and confirm newly synthesized octahedral coordination compounds. NMR method assisted the description of how chalcogen elements (Se and Te) that can replace halogen as inner ligands in forming cluster cores in octahedral cluster complexes. This action reduces the symmetry and makes distortion on the metallic cluster as well as their isomers and of course changes the properties

employed to investigate *Se-*(2-aminoalkyl)selenocysteines as biochemical redox agents [63]. In this case, chalcogen-biochemical substance was investigated through the behavior of its protons and carbons. The similar proton, carbon as well as 77Se spectra recorded, was also

H) carbon (13C) NMR of complex protein molecules were

H or

The intra-molecular chalcogen bonds were obtained from the X-ray diffraction results and quantum chemical calculations, such as in thioindirubin [52], indicating advanced methodology in modern analysis of big molecules. Chalcogen bonds were also studied with the aid of computational programs, as the development of old theories, especially in the debates around the energetic significance and physicochemical origins of the so-called class *σ*-hole interaction [53], continue to fuel scientific discussions. These approaches have served as important steps toward the synthesis, analysis, and designing of new materials [51].
