Preface

In prelude, the purpose of this book is to point out the increasing role of chalcogen elements in multidisciplinary fields such as biogeochemistry, material science, and biochemistry. For these reasons, the book titled 'Chalcogen Chemistry' is structured on a multidisciplinary ap‐ proach by compiling chapters from various contributing authors. The chapters focus on top‐ ics ranging from reactivity to magnetic properties of chalcogens, organic to inorganic (chemistry of chalcogenides), analytical chemistry (qualitative and quantitative analysis), and synthetic to structural and theoretical chemistry (development of new materials). The book is divided into six chapters, each logically and independently presented, and then con‐ cluded with links to new research perspectives as the interest in chalcogen chemistry grows. This book is a valuable source of information not only for chemists but also for materials scientists, physicists, biochemists, and other researchers including biogeochemists, with gen‐ eral or particular interests in chalcogen compounds. I hope the book with a multidisciplina‐ ry approach, comprised of chapters reserved for analytical, materials, biological, and supramolecular chemistry, may induce some curiosity in readers and attract them towards this branch of chemistry.

Chalcogens ('ore builders') are elements that belong to group VI-A (or group 16) in the Peri‐ odic Table. This group consists of oxygen (O), sulfur (S), selenium (Se), tellurium (Te), and polonium (Po). Geometrically, they are known as chalcophiles, which are soft elements (keeping in mind the terminology of the hard/soft acids and bases concept). Thus, chalco‐ philes preferably form minerals with sulfur, selenium, and tellurium. This is the reason why, for a long time, chalcogen chemistry was mostly centred on sulfur, with selenium be‐ ing treated marginally compared to sulfur, whereas the study of the chemistry of tellurium was almost non-existent. However, this consideration has changed over time. Currently, any electronic search on 'SCIfinder' will return a considerable number of scholarly published papers on chalcogen chemistry. In this regard, this book is yet another contribution to ongo‐ ing efforts in the study of chalcogen chemistry.

The interest shown in chalcogen chemistry in the past few years has motivated research fo‐ cused on expanding knowledge on this special class of compounds, and today driving con‐ certed efforts towards new materials development. Chalcogen elements are everywhere in our lives. Firstly, based on their fascinating structural and bonding principles, they span en‐ tire biotic communities connecting chemistry to biogeochemistry, biochemistry, biology, food, agriculture, and also medicine, as well as pharmacology. Secondly, the intensive world‐ wide exploration of chalcogen elements contained in natural compounds as minerals has now shifted the interest towards the development of these new materials or compounds (in combi‐ nation with metals and ligands) with higher physicochemical properties and sophisticated characteristics. Their increased demand with far-reaching economic benefits is owed to their great contribution in modern technology in applications used by a number of industries.

The novelty of this book, compared to general textbooks on chalcogen chemistry, is that principles from other fields of science, such as Analytical Chemistry, are included as a full chapter dedicated to qualitative and quantitative characterisation of chalcogenides and chalcogen materials. This chapter presents modern methods for chalcogen compound analy‐ sis and structural determination. These methods and analytical techniques include: UV-visi‐ ble and infrared spectroscopy (UV/VIS and IR), thermo analysis (TA), electrochemistry (Electrochem), magnetic analysis (MA), chromatography, X-ray methods (mostly XRF, XRD, and EDX), high resolution microscopy (SEM and TEM), multinuclear NMR, computational analysis, and bioassay. The presentation of the chapters in this book is such that there is no arbitrary separation of theoretical concepts (reactivity), chemistry (organic and inorganic), and applications of chalcogens and chalcogen materials (or chalcogenides), and an attempt has been made to stress all three equally. As such, individual chapters have attempted to present the chemistry of the chalcogen(s) or chalcogenide(s), discuss their physicochemical properties (reactivities), as well as their characterisation and applications. Within the chap‐ ters, the theoretical presentation is critically discussed concurrently with emphasis upon the industrial applications in some emerging areas such as in the biomedical, semiconductors, and biogeochemical fields. Insofar as feasible, this is also done with practical examples.

The writing of a text is a humbling experience. In retrospect, the various contributing au‐ thors would agree with me that ideas in the chapters of this book could have only been sourced from a very wide source of literature, as well as from individual research outputs. So, therefore, from the very basic and ethical principle of intellectual honesty, the authors have presented what seemed to them to be the best of their ideas, as well as those of many other authors.

While all the authors have been duly cited and referenced, it is impossible to express ade‐ quately my appreciation for the contributions of all colleagues, graduate and undergraduate students, as well as secretaries, who gave so generously of their time, effort, and opinions. In particular, the help of Ms Lada Bozic in promptly assisting both me and the authors, and handling of the editing platform activities is acknowledged. I know that my attempt to ach‐ ieve depth and quality in the chapter review led to a few of them being declined that may have been considered important by some readers or the authors themselves, I hope that these omissions or inadequacies are few enough so that the usefulness of the presented chapters will not be impaired.

#### **Peter Papoh Ndibewu**

**Chapter 1**

**Provisional chapter**

**Introductory Chapter: Chalcogen Chemistry - The**

**Introductory Chapter: Chalcogen Chemistry - The** 

DOI: 10.5772/intechopen.82542

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

© 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use,

distribution, and reproduction in any medium, provided the original work is properly cited.

**Footprint into New Materials Development**

**1. Chalcogen chemistry – the footprint into new materials** 

The study of chalcogen chemistry is just fascinating for two reasons. Firstly, they span the entire biotic communities connecting chemistry to many other scientific disciplines. These include biogeochemistry, biochemistry, biology, food, agriculture, and also medicine, as well as pharmacology. Secondly, the chalcogen elements known as chalcogens demonstrate extremely interesting properties forming new compounds endowed with sophisticated characteristics that are increasingly making a remarkable footprint in a new era of materials development. These two reasons have intensified worldwide exploration of chalcogen elements contained in natural compounds as minerals. Furthermore, the aforementioned reasons have motivated research focused on expanding knowledge on this special class of compounds. In the past few decades, the shift of interest has been toward the development of new materials (in combination with metals and ligands). The contribution of this field of chemistry to the development of new materials, and their impacts on the everyday life of mankind, has triggered a recent renaissance of the interconnectivity between new chemical concepts and reactivities, resulting in a multitude of multidisciplinary focused research niche areas. The unique structures and reactivity of the class of chalcogen compounds and materials [1, 2] as well as their fascinating optical [3, 4] and electronic properties [5, 6] confer onto them very

Group 16 or group VI-(A) elements in the modern periodic table comprising of oxygen (O), sulfur (S), selenium (Se), tellurium (Te), and polonium (Po) are usually called chalcogens ("ore builders") [13, 14]. The most valuable fundamental characteristic of these elements is their versatile nature to form new bonds and new compounds [15–17]. In this regard and

**Footprint into New Materials Development**

Additional information is available at the end of the chapter

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/intechopen.82542

wide potential applications [7–12].

Ndibewu Peter Papoh

Ndibewu Peter Papoh

**development**

Department Chemistry, Arcadia Campus Professor, Departments of Chemistry, Chemical & Metallurgical Engineering Tshwane University of Technology Pretoria, South Africa

#### **Introductory Chapter: Chalcogen Chemistry - The Footprint into New Materials Development Introductory Chapter: Chalcogen Chemistry - The Footprint into New Materials Development**

DOI: 10.5772/intechopen.82542

Ndibewu Peter Papoh

characteristics. Their increased demand with far-reaching economic benefits is owed to their great contribution in modern technology in applications used by a number of industries.

The novelty of this book, compared to general textbooks on chalcogen chemistry, is that principles from other fields of science, such as Analytical Chemistry, are included as a full chapter dedicated to qualitative and quantitative characterisation of chalcogenides and chalcogen materials. This chapter presents modern methods for chalcogen compound analy‐ sis and structural determination. These methods and analytical techniques include: UV-visi‐ ble and infrared spectroscopy (UV/VIS and IR), thermo analysis (TA), electrochemistry (Electrochem), magnetic analysis (MA), chromatography, X-ray methods (mostly XRF, XRD, and EDX), high resolution microscopy (SEM and TEM), multinuclear NMR, computational analysis, and bioassay. The presentation of the chapters in this book is such that there is no arbitrary separation of theoretical concepts (reactivity), chemistry (organic and inorganic), and applications of chalcogens and chalcogen materials (or chalcogenides), and an attempt has been made to stress all three equally. As such, individual chapters have attempted to present the chemistry of the chalcogen(s) or chalcogenide(s), discuss their physicochemical properties (reactivities), as well as their characterisation and applications. Within the chap‐ ters, the theoretical presentation is critically discussed concurrently with emphasis upon the industrial applications in some emerging areas such as in the biomedical, semiconductors, and biogeochemical fields. Insofar as feasible, this is also done with practical examples.

The writing of a text is a humbling experience. In retrospect, the various contributing au‐ thors would agree with me that ideas in the chapters of this book could have only been sourced from a very wide source of literature, as well as from individual research outputs. So, therefore, from the very basic and ethical principle of intellectual honesty, the authors have presented what seemed to them to be the best of their ideas, as well as those of many

While all the authors have been duly cited and referenced, it is impossible to express ade‐ quately my appreciation for the contributions of all colleagues, graduate and undergraduate students, as well as secretaries, who gave so generously of their time, effort, and opinions. In particular, the help of Ms Lada Bozic in promptly assisting both me and the authors, and handling of the editing platform activities is acknowledged. I know that my attempt to ach‐ ieve depth and quality in the chapter review led to a few of them being declined that may have been considered important by some readers or the authors themselves, I hope that these omissions or inadequacies are few enough so that the usefulness of the presented

Professor, Departments of Chemistry, Chemical & Metallurgical Engineering

**Peter Papoh Ndibewu**

Pretoria, South Africa

Department Chemistry, Arcadia Campus

Tshwane University of Technology

other authors.

VIII Preface

chapters will not be impaired.

Additional information is available at the end of the chapter Ndibewu Peter PapohAdditional information is available at the end of the chapter

http://dx.doi.org/10.5772/intechopen.82542
