Conformer Distribution in Rotaxanes Containing Nonsymmetric Threads: A Systematic Approach

Orlando, Tainára; Salbego, Paulo R. S.; Zimmer, Geórgia C.; Pagliari, Anderson B.; Bender, Caroline R.; Rodrigues, Leticia V.; Bonacorso, Hélio G.; Zanatta, Nilo; Berná, José; Martins, Marcos A. P.

doi:10.1002/ejoc.201800991

Cited by 12 publications

(59 citation statements)

References 43 publications

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“…It is observed that in the case of crystal structures of rotaxanes, studies have been restricted mainly at the molecular level (intramolecular or intercomponent interactions), by means of molecular dynamic in solution,, , in the solid state, and theoretical studies . Intermolecular environments – despite great progress in other fields – are commonly neglected or discussed showing motifs from specific interactions with the aid of just geometric data , .…”

Section: Introductionmentioning

confidence: 99%

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Crystallization Mechanisms Applied to Understand the Crystal Formation of Rotaxanes

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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: Introductionmentioning

confidence: 99%

“…Rotaxanes with solvent molecules in their crystal structures (i.e., solvates) are also widely reported in the literature, , . Nevertheless, little attention has been given to this topic regarding the investigation of when and why solvent molecules crystallize with the rotaxane molecule.…”

Section: Introductionmentioning

confidence: 99%

Crystallization Mechanisms Applied to Understand the Crystal Formation of Rotaxanes

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“…For example, we have recently shown that the flanking chains on an encapsulated squaraine dye can undergo back‐folding and form stabilizing interactions with the surrounding macrocycle . Similarly, work on structurally related tetralactam rotaxanes has reported evidence for interactions between the ends of the encapsulated thread and the surrounding macrocycle , , . It is worth noting that our previous study of rotaxane 1 also observed broad NMR peaks for dye protons 2, 3 and 5 but the published report did not offer a structural explanation .…”

Section: Resultsmentioning

confidence: 86%

“…Notably, the peaks for protons 1 and 2 on C2 and protons E and F on M are shifted upfield due to changes in aromatic ring shielding caused by threading. In addition, the peaks for protons C and D on M are shifted downfield due to hydrogen bonding interactions with the oxygens atoms on the encapsulated croconaine , . Another expected feature of the NMR spectral pattern for M⊃C2 is the appearance of many of the signals as multiple peaks .…”

Section: Resultsmentioning

confidence: 99%

Croconaine Rotaxane Dye with 984 nm Absorption: Wavelength‐Selective Photothermal Heating

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Croconaines are an emerging class of near‐infrared dyes that are useful for various sensing, photothermal, optoelectronic, and photoacoustic applications. Previous work encapsulated a dumbbell‐shaped croconaine dye whose structure contains two thiophene flanking units inside a tetralactam macrocycle and produced a croconaine rotaxane 1 with a narrow 824 nm absorption band. Herein, a new rotaxane 2 is reported that encapsulates a croconaine dye with two thienothiophene flanking units. The new croconaine rotaxane 2 exhibits a narrow 984 nm absorption band that is distinct from the 824 nm absorption of rotaxane 1. Photothermal heating experiments showed that an 830 nm diode laser selectively heats a solution containing rotaxane 1, with no heating of a solution containing rotaxane 2. Conversely, a 980 nm diode laser selectively heats a solution containing rotaxane 2, with no heating of a solution containing rotaxane 1. The new croconaine rotaxane 2 shows no fatigue after four cycles of laser heating and cooling.

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“…However, in the last years, our research group reported studies classifying these interactions as trifurcated hydrogen bonds (Figure b) by means of energetic data. Stabilization energy values for trifurcated systems based on two N–H ··· O and one C–H ··· O interaction were discussed .…”

Section: Introductionmentioning

confidence: 99%

[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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Conformer Distribution in Rotaxanes Containing Nonsymmetric Threads: A Systematic Approach

Cited by 12 publications

References 43 publications

Crystallization Mechanisms Applied to Understand the Crystal Formation of Rotaxanes

Crystallization Mechanisms Applied to Understand the Crystal Formation of Rotaxanes

Croconaine Rotaxane Dye with 984 nm Absorption: Wavelength‐Selective Photothermal Heating

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

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