**6. Applications of solvent effects in supramolecular systems**

Except of publications that are indicative of scientific activity for furthering the knowledge base, patents are indicative of technology development for commercial

**223**

**7. Conclusion**

**Figure 19.**

**Table 1.**

*Solvent Effects in Supramolecular Systems DOI: http://dx.doi.org/10.5772/intechopen.86981*

*Summary of the patent search results.*

or market potential. On this basis a patent search has been conducted so as to map the transition between science, technology, and market. For this purpose, we used the same parameters for our patent data extraction through Patsnap, a patent search engine and analytic portal. Using this patent search engine, an extended patent search in available patent libraries such as the European Patent Office, USPTO, and FPO was conducted. From this analysis it is evident that the sector supramolecular chemistry has started to grow significantly in recent years. The patent search followed a four-level approach starting by available patents using the following keywords: supramolecular complexes, solvatochromism, rotaxane/catenane, and solvatochromic rotaxane/catenane (**Table 1**). This refinement drives us to the specific market and indicates us the freedom to operate since by this procedure we conclude on the presence of very few patents that are mainly filled in the United

**Keyword Simple Total** Supramolecular complexes 4682 16,727 Solvatochromism 296 806 Rotaxane/catenane 165 587 Solvatochromic Rotaxanes/catenanes 4 7

*Patent search results: rotaxane/catenane (left) and solvatochromic rotaxane/catenane (right).*

States and China. The corresponding landscape is shown in **Figure 19**.

In this chapter, we reviewed some important examples of how solvents can influence supramolecular processes and structures. The impact of solvents on supramolecular binding is the starting point through which it is made clear that altering solvent polarity can drastically influence supramolecular binding processes. Solvents can also affect the relative supramolecular conformations of complex systems allowing the development of medium responsive molecular machines and switches. Moreover, solvents can give rise to supramolecular solvatochromic phenomena leading to optical changes and this observation has significantly assisted in the development of solvent (environment) sensing supramolecular systems. Last but not least, various metal ion-involving supramolecular architectures can be drastically influenced by specific solvents or solvent/cosolvent mixtures. This key effect

*Solvent Effects in Supramolecular Systems DOI: http://dx.doi.org/10.5772/intechopen.86981*


**Table 1.**

*Solvents, Ionic Liquids and Solvent Effects*

solvent is employed as cosolvent [63].

*with permission from: Papadakis et al. [65].*

**Figure 18.**

long ago [64]. Such CTCs involving [FeII(CN)6]

solvents were obtained: [Mn(*ppt*)2(DMF)1/2(H2O)3]*m* and [Mn(*ppt*)2(toluene)1/2(M eOH)3/2]*k*, respectively. This interesting phenomenon was attributed to the fact that when only an aprotic solvent is utilized, the neighboring 2D polymer grid-sheets in [Mn(*ppt*)2]*n* are stacked in a staggered mode, and this leads to a very compact 3D structure leaving out the solvent molecules. This effect is avoided when a protic

*(A) The zigzag (…HOH…HCF…)*<sup>n</sup> *polymers involved in a viologen/HCF CTC reported by Papadakis et al. (hydrogen atoms have been omitted). A cluster consisting of four viologen molecules around a HCF anion and the corresponding Hirshfeld surface representations shown along the b-(B), a-(C) and c-(D) axis. Reprinted* 

In all above examples, the coordination of solvent molecules to the metal centers

<sup>4</sup><sup>−</sup> (HCF) as a strong electron

was found to affect the structure of the supramolecular coordination systems. Secondary interactions, which were already mentioned, mainly account to the H-bonding of a coordinating solvents and non-coordinating cosolvent. There are several cases however where secondary interactions alone can lead to stabilized 3D supramolecular coordination structures. The supramolecular charge transfer complexes (CTCs) of viologens with various electron donors have been reported

donor have been given some attention; however, their supramolecular structure has been scarcely investigated so far. An example pertaining to this category of supramolecular CTCs was recently reported by Papadakis et al. [65]. As depicted in **Figure 18**, the nonsymmetric dicationic viologen molecules tend to aggregate around the anionic HCF donor. However, the stability of a crystalline structure of such a CTC is achieved only if water is introduced in the reaction mixture. Water is found to readily form H-bonds with CN groups of HCF, and this results in the formation of a zigzag 2D polymer of the type: (…HOH…HCF…)*n*. The 3D supramolecular structure comprises the described 2D polymers and cationic channels of viologens perpendicular to these 2D polymers (**Figure 18**). Attempts to remove (by drying) or replace water (employing even another protic solvent) in these structures failed. Apparently the stabilizing interaction in these supramolecular systems is H-bonding which is stronger when H2O is utilized. The importance of H2O and the formation of a CTC in a similar fashion have been also reported earlier by Abouelwafa et al. [66]. In the aforementioned example, a symmetric viologen

**6. Applications of solvent effects in supramolecular systems**

Except of publications that are indicative of scientific activity for furthering the knowledge base, patents are indicative of technology development for commercial

**222**

was utilized instead [66].

*Summary of the patent search results.*

**Figure 19.**

*Patent search results: rotaxane/catenane (left) and solvatochromic rotaxane/catenane (right).*

or market potential. On this basis a patent search has been conducted so as to map the transition between science, technology, and market. For this purpose, we used the same parameters for our patent data extraction through Patsnap, a patent search engine and analytic portal. Using this patent search engine, an extended patent search in available patent libraries such as the European Patent Office, USPTO, and FPO was conducted. From this analysis it is evident that the sector supramolecular chemistry has started to grow significantly in recent years. The patent search followed a four-level approach starting by available patents using the following keywords: supramolecular complexes, solvatochromism, rotaxane/catenane, and solvatochromic rotaxane/catenane (**Table 1**). This refinement drives us to the specific market and indicates us the freedom to operate since by this procedure we conclude on the presence of very few patents that are mainly filled in the United States and China. The corresponding landscape is shown in **Figure 19**.
