Azo group(s) in selected macrocyclic compounds

Wagner‐Wysiecka, Ewa; Łukasik, Natalia; Biernat, Jan F.; Luboch, Elżbieta

doi:10.1007/s10847-017-0779-4

Cited by 83 publications

(56 citation statements)

References 275 publications

(316 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…[44][45][46][47] In recent years, photoswitchable macrocyclic systems with multiple ABs have been explored experimentally because of their potential applications in supramolecular chemistry, molecular machines, etc. 6,[48][49][50][51] These AB units are usually linked by chemical bonds, which thus leads to remarkable steric interaction and ring strain. Very recently, Slavov et al have employed timeresolved absorption spectroscopy to explore the excited-state dynamics of a macrocyclic biazobenzene molecule (CBA) as shown in Figure 1.…”

Section: Introductionmentioning

confidence: 99%

Stereoselective Excited-State Isomerization and Decay Paths in cis-Cyclobiazobenzene

Zhang

Qiu

et al. 2019

J. Phys. Chem. A

View full text Add to dashboard Cite

Herein we have employed OM2/MRCI-based full-dimensional nonadiabatic dynamics simulations to explore the photoisomerization and subsequent excited-state decay of a macrocyclic cyclobiazobenzene (CBA) molecule. Two S1/S0 conical intersection structures are found to be responsible for the excited-state decay. Related to these two conical intersections, we found two stereoselective photoisomerization and excited-state decay pathways, which correspond to the clockwise and counterclockwise rotation motions with respect to the N=N bond of the azo group. In both pathways the excited-state isomerization is ultrafast and finishes within ca. 69 fs; but, the clockwise isomerization channel is much more favorable than the counterclockwise one with a ratio of 74% vs. 26%. Importantly, the present work demonstrates that stereoselective pathways exist not only in the photoisomerization of isolated azobenzene-like systems but also in macrocyclic systems with multiple azobenzenes (ABs). This finding could provide useful insights for understanding and controlling the photodynamics of macrocyclic nanostructures with AB units as the main building units.

show abstract

Section: Introductionmentioning

confidence: 99%

Stereoselective Excited-State Isomerization and Decay Paths in cis-Cyclobiazobenzene

Zhang

Qiu

et al. 2019

J. Phys. Chem. A

View full text Add to dashboard Cite

show abstract

“…[27,28] Here, a polarizable azobenzene (azo) chromophore was employed to impose a dipole moiety via the protonation process of molecule. [29] Azo is a classic pH indicator dye, [30,31] but its application is severely limited due to its poor water solubility and serious aggregations after protonation. [32,33] In our demonstration, the azo molecules were directly anchored on the sensor surface (SiO 2 ) to avoid the solubility and aggregation issues.…”

Section: Knowledge Of Interfacial Interactions Between Analytes and Fmentioning

confidence: 99%

Synergy of Ionic and Dipolar Effects by Molecular Design for pH Sensing beyond the Nernstian Limit

et al. 2019

View full text Add to dashboard Cite

interface generates original signal and plays a crucial role in the sensing process. In ion sensors, the interaction between ions and ion receptors can lead to accumulation of interfacial charges, thereby causing an interfacial potential change that can be electronically readout. [3] A versatile sensing platform can also be designed by functionalizing the sensor surface with self-assembled organic monolayers (SAMs), which offers the possibility to tailor the chemical and/or physical interactions of the sensor surface with analytes. These interfacial interactions can generate additional changes in surface dipoles and/or charges on the sensing surface, [4,5] which can in turn affect the electrical properties of the surface and tune the sensitivity. [6][7][8] It can be emphasized that both surface charge and dipole play an equally important role in establishing the surface equilibrium state. The dipole effect can be engineered in a controllable and systematic way. Therefore, modulating the molecular dipole moment to enhance device performance holds promises in numerous applications. [9][10][11] However, the molecular dipole effect is strongly dependent on multiple parameters in practice, such as dipole orientation, distribution, and packing density of each molecule within the SAM. [12,13] These parameters are strongly inter-correlated. For example, increasing the dipole moment of the surface immobilized molecules can enhance the electrostatic repulsions between neighboring dipoles, influence the packing density, and even change the configuration of the SAM. Thus, in order to engineer the interfacial dipole in a controllable manner, a rational design of the system is needed.Since the dipole moment originates from the charge separation between atoms due to their difference in electronegativity, changing the electronegativity on the molecular substituent can be an efficient way to modulate the molecular dipole. A dipole moment can also be formed by ion pair of cation and anion, [14,15] which can be embodied by a well-known phenomenon that the electrostatic attraction between cations and anions can lead to a significant change in surface wettability. [16,17] This ionic dipole is strongly dependent on the polarizability of the ionic pair, and is affected by the properties of the ions such as ionic radius and hydration energy. [18,19] Therefore, artificial designs to form ion pairs can be an alternative to create dipoles on the sensing surface for modulation of its sensitivity. With proper molecular Knowledge of interfacial interactions between analytes and functionalized sensor surfaces, from where the signal originates, is key to the development and application of electronic sensors. The present work explores the tunability of pH sensitivity by the synergy of surface charge and molecular dipole moment induced by interfacial proton interactions. This synergy is demonstrated on a silicon-nanoribbon field-effect transistor (SiNR-FET) by functionalizing the sensor surface with properly designed chromophore molecules. The ch...

show abstract

“…18 The impact of ring strain on cyclic AB-polymers has been discussed in the past by Rau, 11,12 Nobuyuki 13,14 and others. 19,20 More recently, experimental 21 and computational [22][23][24][25] work described the photo-isomerization of a bridged-AB, in which the two phenyl rings are connected with an alkyl chain. The constrained AB presented several advantages compared to the acyclic AB: the band separation was larger, the quantum yield was enhanced, and the photo-isomerization was faster.…”

Section: Introductionmentioning

confidence: 99%

Tuning the Thermal Stability and Photoisomerization of Azoheteroarenes through Macrocycle Strain

Vela¹,

Scheidegger²,

Fabregat³

et al. 2020

Preprint

View full text Add to dashboard Cite

Azobenzene and its derivatives are one of the most-widespread molecular scaffolds in a range of modern applications, as well as in fundamental research. After photoexcitation, azo-based photoswitches revert back to the most stable isomer in a timescale (t1/2) that determines the range of potential applications. Attempts to bring t1/2 to extreme values prompted to the development of azobenzene and azoheteroarene derivatives that either rebalance the E- and Z- isomer stabilities, or exploit unconventional thermal isomerization mechanisms. In the former case, one successful strategy has been the creation of macrocycle strain, which tends to impact the E/Z stability asymmetrically, and thus significantly modifies t1/2. On the bright side, bridged derivatives have shown an improved optical switching owing to the higher quantum yields and absence of degradation. However, in most (if not all) cases, bridged derivatives display a reversed thermal stability (more stable Z-isomer), and smaller t1/2 than the acyclic counterparts, which restricts their potential interest to applications requiring a fast forward and backwards switch. In this paper, we investigate the impact of alkyl bridges to the thermal stability of phenyl-azoheteroarenes using computational methods, and we reveal that is indeed possible to combine such improved photo-switching characteristics while preserving the regular thermal stability (more stable E-isomer), and increased t1/2 values under the appropriate connectivity and bridge length.

show abstract

Azo group(s) in selected macrocyclic compounds

Cited by 83 publications

References 275 publications

Stereoselective Excited-State Isomerization and Decay Paths in cis-Cyclobiazobenzene

Stereoselective Excited-State Isomerization and Decay Paths in cis-Cyclobiazobenzene

Synergy of Ionic and Dipolar Effects by Molecular Design for pH Sensing beyond the Nernstian Limit

Tuning the Thermal Stability and Photoisomerization of Azoheteroarenes through Macrocycle Strain

Contact Info

Product

Resources

About