This thesis entitled ‘The synthesis and study of novel squaramide-based anion sensors’ is divided into five chapters. Chapter 1 gives a brief introduction of the significance of anions in biology, environment and industry which elicits the history, development and challenge of anion sensing and recognition. The mechanism of H-bonding interaction based anion sensing and recognition are particularly discussed, followed by the introduction of a series examples of anion receptors and sensors containing functional groups with the capability of H-bonding to anions. As the core of this research, squaramide-based anion receptors and sensors are particularly discussed. This chapter ends with the aims and objectives of the research conducted in Chapter 2 and 3. In Chapter 2, the design and synthesis of novel squaramidoquinoxaline (SQX) moiety based anion sensors are discussed. All desired compounds are synthesized through an efficient two step synthetic protocol and fully characterized. The characterization of their photophysical and anion binding properties reveals the -NO2 substituted compound to be an interesting candidate . In particular, crystal structure study and F- test strips study of the -NO2 substituted compound are also discussed in this chapter. Chapter 3 discusses the design and synthesis of macrocyclic squaramide (MSQ) moiety based anion sensors. At the beginning, the nitro and dinitro substituted MSQs are synthesized and characterized due to -NO2 substituted SQX showed great interest in Chapter 2. The preliminary attempts to synthesize fluorescent probe substituted MSQ which is capable of carrying out Förster Resonance Energy Transfer (FRET) are also discussed in this chapter. In addition, the anion binding properties of successfully synthesized MSQs are studied. Chapter 4 gives an overall conclusion of the entire work carried out in this research and also offers the idea for future work. In Chapter 5, the instrumentation, reagents, general experimental procedures and characterization of each compound discussed in this thesis are given.