Anions are ubiquitous in biology, medicine, catalysis and the environment. Due to their importance in a variety of areas, the selective recognition, sensing and transport of anions has been a burgeoning area of research for decades, especially in the field of supramolecular chemistry. Among the increasing and diverse synthetic anion binding receptors, the squaramide moiety is gaining popularity in recent years due to various advantageous characteristics that render it useful for anion binding. This thesis will focus on the synthesis of several families of a novel peptidomimetic hybrid between peptides and squaramides; so-called squaratide receptors where their anion binding behavior will be analyzed in detail. The thesis will start with a literature review of anions and synthetic anion binding receptor design and then concentrates on recently reported squaramide anion binding receptors. The introduction of aims and objectives of the research will follow. Chapter 2 introduces a novel family of cyclic squaratide dimers as anion binding receptors using amino acids, squaramide, and ethylenediamine as building blocks. The receptors were synthesized by facile and reliable methods and their structures were fully characterized. The crystal structure of one of the dimers was obtained which revealed the solid-state conformation of this macrocycle. The anion binding performance of the dimers was examined by 1H NMR anion titrations, in which an abnormal shift of the amide NH protons was observed. The results were plotted by the function of anion concentration and were fitted using the open-access software BindFit to simulate their binding stoichiometry. The cyclic squaratide dimers were found to selectively bind to acetate and benzoate while displaying a moderate affinity for chloride and a rather weak affinity for sulfate. This behavior was not anticipated when comparing to previously reported cyclic squaramide and peptide containing squaramide receptors. Chapter 3 introduces acyclic squaratide dimers based on their cyclic counterparts reported in Chapter 2. The receptors were synthesized by coupling two similar monomers of amino acid-squaramide-ethylenediamine monomers. The binding performance was explored by 1H NMR titrations where the acyclic squaratide dimers showed relatively weak overall selectivity and affinity for variously anions compared to their cyclic analogues. This has proven the importance of cyclic structure as a method of pre-organization of binding sites in anion binding receptors. By comparing the 1H NMR spectra of cyclic and acyclic squaratide dimers, a postulation was put forward about the intramolecular hydrogen bonding within the cyclic squaratide dimers and its impact on the anion recognition and binding process, which eventually caused a possible conformational change as well as the previously mentioned abnormal shift of amide NH protons in Chapter 2. Chapter 4 introduces the cyclic squaratide polymers in order to exploit the availability of enlarging the binding cavity and the addition of hydrogen bond donors. Trimers and tetramers of L-Phe, D-Phe and Boc-Lys derivatives were successfully prepared by solid phase peptide synthesis method and the polymers were characterized by a variety of means such as NMR, IR and HRMS. The anion titrations were performed where the chirality of L/D-Phe polymers was found not playing an important role in anion recognition and binding selectivity. The overall anion binding performance of cyclic squaratide polymers were outmatched by cyclic squaratide dimers, which was attributed to over-enlarged cavity and complicated binding behavior brought by multiple anion binding sites. Chapter 5 explores the binding performance of several bis-amino acid squaramide compounds which were reported a long time ago yet were never considered as anion binding receptors. The anion titrations of these compounds displayed of high affinity, yet complicated binding behaviors for oxoanions like phosphate monobasic, acetate and benzoate anions. An esterified bis-AA squaramide receptor, bis-(Ala-OMe) squaramide was then synthesized as a control and was titrated with acetate and turned out to display simplified binding behavior and improved binding affinity for acetate, revealing that the carboxylic groups in bis-AA squaramides were interfering the anion recognition and binding, thus complicating the overall anion binding behaviors.