Novel Quinolizine AIE System: Visualization of Molecular Motion and Elaborate Tailoring for Biological Application

Molecular motions are ubiquitous in nature and they immutably play intrinsic roles in all actions. However, exploring appropriate models to decipher molecular motions is an extremely important but very challenging task for researchers. Considering aggregation-induced emission (AIE) luminogens possess their unique merits to visualize molecular motions, it is particularly fascinating to construct new AIE systems as model to study molecular motion. Herein, a novel quinolizine (QLZ) AIE system was constructed based on the restriction intramolecular vibration mechanism. It was demonstrated that QLZ could act as an ideal model to visualize single-molecule motion and macroscopic molecular motion via fluorescence change. Additionally, further elaborate tailoring of this impressive core achieved highly efficient reactive oxygen species production and realized fluorescence imaging-guided photodynamic therapy applications, which confirms the great application potential of this new AIE-active QLZ core. Therefore, this work not only provides an ideal model to visualize molecular motion but also opens a new way for the application of AIEgens.

Comparative analysis of dielectric, shear mechanical and light scattering response functions in polar supercooled liquids

The studies of molecular dynamics in the vicinity of liquid–glass transition are an essential part of condensed matter physics. Various experimental techniques are usually applied to understand different aspects of molecular motions, i.e., nuclear magnetic resonance (NMR), photon correlation spectroscopy (PCS), mechanical shear relaxation (MR), and dielectric spectroscopy (DS). Universal behavior of molecular dynamics, reflected in the invariant distribution of relaxation times for different polar and weekly polar glass-formers, has been recently found when probed by NMR, PCS, and MR techniques. On the other hand, the narrow dielectric permittivity function ε*(f) of polar materials has been rationalized by postulating that it is a superposition of a Debye-like peak and a broader structural relaxation found in NMR, PCS, and MR. Herein, we show that dielectric permittivity representation ε*(f) reveals details of molecular motions being undetectable in the other experimental methods. Herein we propose a way to resolve this problem. First, we point out an unresolved Johari–Goldstein (JG) β-relaxation is present nearby the α-relaxation in these polar glass-formers. The dielectric relaxation strength of the JG β-relaxation is sufficiently weak compared to the α-relaxation so that the narrow dielectric frequency dispersion faithfully represents the dynamic heterogeneity and cooperativity of the α-relaxation. However, when the other techniques are used to probe the same polar glass-former, there is reduction of relaxation strength of α-relaxation relative to that of the JG β relaxation as well as their separation. Consequently the α relaxation appears broader in frequency dispersion when observed by PCS, NMR and MR instead of DS. The explanation is supported by showing that the quasi-universal broadened α relaxation in PCS, NMR and MR is captured by the electric modulus M*(f) = 1/ε*(f) representation of the dielectric measurements of polar and weakly polar glass-formers, and also M*(f) compares favorably with the mechanical shear modulus data G*(f).

Gravitational Force is a Type of Physical Interaction between Gluon Fields: Molecular Motions of Gases

This study presents a Gluon Gravity Model, to explain the mechanism of gravity. With the development of quantum chromodynamics since 1970, Newton's law of universal gravitation and Einstein's theory of general relativity need to be reinterpreted. Like an electric charge causes an electric field, the color charges in quantum chromodynamics were introduced into the gravitational field. The gluons mediating strong force can bring about a new color field around the strong force field owing to their color charges. This new color field of charges becomes a gravitational field in Gluon Gravity Model. This model is supported by the facts that most of the atomic mass is composed of the gluon field energy and the similarity between the two formulas of Coulomb's law and Newton's laws of universal gravitation. Additionally, it is possible to explain the gas molecular motions by applying the Gluon Gravity Model to the gluon fields within a proton.

The never-ending quest to understand the shapes and motions of molecules

Why is it so important to know the shape of molecules? How can virtual reality and advances in scientific visualization help? These are recurrent questions about the importance of understanding molecular shapes and molecular motions. In this brief feature article some background is provided to better understand the central role played by visual and computational analysis of molecular structures. The role of hardware devices and software tools to assist scientists in this quest is pointed out, along with challenges to share visual experiences more broadly. These topics touch upon many current questions in research. Examples related to biological membranes, molecular medicine, -omics data and SARS-Cov-2 structural data are provided to illustrate convincing use cases.