Polymorphism in a Rotaxane Molecule: Intra- and Intermolecular Understanding

Orlando, Tainára; Salbego, Paulo R. S.; Taschetto, Carmen L. R.; Bonacorso, Hélio G.; Zanatta, Nilo; Hoerner, Manfredo; Martins, Marcos A. P.

doi:10.1021/acs.cgd.8b01560

Cited by 19 publications

(43 citation statements)

References 42 publications

(109 reference statements)

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“…The majority of the analyzed structures presented a decrease of energetic influence on crystal formation and higher topological contribution (contact area), with NG/NC values below 1.0 at stage II. These values were expected and commonly reported in this advanced stage due to approximation of the formed stable blocks , . In fact, complementarity between large contact areas are more significant than specific intermolecular interactions in the last stages …”

Section: Resultssupporting

confidence: 84%

“…These values were expected and commonly reported in this advanced stage due to approximation of the formed stable blocks , . In fact, complementarity between large contact areas are more significant than specific intermolecular interactions in the last stages …”

Section: Resultssupporting

confidence: 84%

“…This is different from the behavior of smaller molecules previously described by our research group , , , . The formation of one‐dimensional blocks corroborates with crystallization mechanisms proposed for polymorphs of [2]rotaxanes recently reported …”

Section: Resultssupporting

confidence: 77%

“…A large contact area involved in the molecule interactions in the first steps of crystallization was observed, making it difficult for unique interactions to direct crystal formation, which is different from what is easily observed in other classes of small molecules, such as triazenes N ‐oxides . With the study of different classes of structures using this approach, some patterns may be observed and generic crystallization routes summarized for the investigated organic crystal structures (Figure ).…”

Section: Resultsmentioning

confidence: 97%

“…It was proposed crystallization mechanisms using a retrocrystallization process, which uses formed crystal data to presume how the stages of crystallization process occurred. Some investigations reported by our research group proposed crystallization mechanisms for a series of isoxazoles, triazenes N ‐oxides, substituted pyrazoles, N ‐phenilamides, and polymorph of [2]rotaxane …”

Section: Resultsmentioning

confidence: 99%

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Crystallization Mechanisms Applied to Understand the Crystal Formation of Rotaxanes

et al. 2019

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The present study discusses the crystalline packing formation of several [2]rotaxanes with Leigh‐type tetralactam macrocycle bearing different threads. The presence of solvent molecules in some structures are also addressed to shed some light on this matter. Additionally, the degree of similarity between supramolecular structures of rotaxanes was discussed using similarity indices. For this, new descriptors and crystallization mechanisms, which were proposed in terms of contact area and stabilization energy, were carried out to evaluate the rotaxane molecules. It was possible to observe similar general stages of crystallization dominated by the formation of 1D‐blocks and, in fewer cases, by dimers in the first stage of nucleation. The preference for the formation of 1D nuclei resides in the large contact area and complementarity involved in the large set of interactions between the rotaxanes at the earliest stages of crystallization. In this context, it was possible to propose when solvent molecules are trapped between the rotaxanes during crystal formation. Therefore, a unique example of a rotaxane whose topology favored the entrapment of water molecules between rotaxanes during the first stage of the crystallization process is presented. Crystallization mechanisms showed to be a valuable asset in the supramolecular investigation of rotaxanes in the crystalline state.

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Section: Resultssupporting

confidence: 84%

Section: Resultssupporting

confidence: 84%

Section: Resultssupporting

confidence: 77%

Section: Resultsmentioning

confidence: 97%

Section: Resultsmentioning

confidence: 99%

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Crystallization Mechanisms Applied to Understand the Crystal Formation of Rotaxanes

et al. 2019

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Thermally and Photochemically Induced Dethreading of Fumaramide‐Based Kinetically Stable Pseudo[2]rotaxanes

et al. 2019

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The thermally and photochemically induced dethreading of a series of pseudo[2]rotaxanes bearing tetraalkyl‐substituted fumaramide axles and polyamide macrocycles is reported herein. The length of the alkyl chains at the ends of the thread, the void size, and flexibility of the macrocycle and the intercomponent interactions are critical for a satisfactory dethreading process. 1H NMR kinetic experiments were carried out in order to calculate the rate constants of the thermal dethreading processes and stabilities of the rotaxanes, by comparing with the similar data for the deslipping of the succinamide surrogates. The deslipping reaction occurs faster with the fumaramide systems than succinamide ones. The incorporation of adamantane moieties into the polyamide macrocycle drastically slowed down the disconnecting process. Furthermore, interlocked systems with dipropylamino groups as stoppers experienced a rapid dethreading when irradiated under UV‐light, a process triggered by the fumaramide–maleamide isomerization. In this case, the n‐propyl groups are not bulky enough to keep together both components as the number of hydrogen bonds between thread and macrocycle is halved in the maleamide systems.

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[2]Rotaxanes Bearing a Tetralactam Macrocycle: The Role of a Trifurcated Hydrogen Bond in the Crystalline State

et al. 2019

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This study investigated the proper classification and quantification of intercomponent trifurcated hydrogen bonds, in the crystalline state, of rotaxanes bearing a tetralactam Leigh‐type macrocycle. Quantum mechanical calculations were carried out to obtain the interaction paths and their stabilization energies. In general, the use and necessity of fragmentation in types of interaction have been reported in the literature, although they are commonly performed only using a geometric approach. This results in N–H···O interactions that are indicated as the main interactions between components, neglecting other possible interactions. The use of energetic fragmentation was demonstrated here under an appropriate demarcation considering all interactions and showing the existence and role of the C–H···O interaction. The C–H···O interactions showed similar energy to N–H···O interactions with average values around –4.75 kcal mol–1 and –4.60 kcal mol–1, respectively. This revealed that the three hydrogen bonds are part of a cooperative set of interactions with a similar contribution. The trifurcated hydrogen bonds presented high contribution in the total intercomponent stabilization energy of the rotaxanes, with an average value of 51 % in the studied series.

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Polymorphism in a Rotaxane Molecule: Intra- and Intermolecular Understanding

Cited by 19 publications

References 42 publications

Crystallization Mechanisms Applied to Understand the Crystal Formation of Rotaxanes

Crystallization Mechanisms Applied to Understand the Crystal Formation of Rotaxanes

Thermally and Photochemically Induced Dethreading of Fumaramide‐Based Kinetically Stable Pseudo[2]rotaxanes

[2]Rotaxanes Bearing a Tetralactam Macrocycle: The Role of a Trifurcated Hydrogen Bond in the Crystalline State

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