다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

The halogen bond occurs when there is evidence of a net attractive interaction between an electrophilic region associated with a halogen atom in a molecular entity and a nucleophilic region in another, or the same, molecular entity. In this fairly extensive review, after a brief history of the interaction, we will provide the reader with a snapshot of where the research on the halogen bond is now, and, perhaps, where it is going. The specific advantages brought up by a design based on the use of the halogen bond will be demonstrated in quite different fields spanning from material sciences to biomolecular recognition and drug design.

The Halogen Bond

THE JOURNAL OF BIOLOGICAL CHEMISTRY: The Biochemical Behavior of LeadL I. Influence of Calcium, Phosphorus, and Vitamin D on Lead in Blood and Bone

Recent Developments in the Preparation and Chemistry of Metallacycles and Metallacages via Coordination

The w(hole) picture: A tetrel bond is a directional noncovalent interaction between a covalently bonded atom of Group IV and a negative site, for example, the lone pair of a Lewis base or an anion. It involves a region of positive electrostatic potential (σ hole), and energetically, they are comparable to hydrogen bonds and other σ-hole-based interactions.

Tetrel‐Bonding Interaction: Rediscovered Supramolecular Force?

Non-covalent interactions play a crucial role in (supramolecular) chemistry and much of biology. Supramolecular forces can indeed determine the structure and function of a host–guest system. Many sensors, for example, rely on reversible bonding with the analyte. Natural machineries also often have a significant non-covalent component (e.g. protein folding, recognition) and rational interference in such ‘living’ devices can have pharmacological implications. For the rational design/tweaking of supramolecular systems it is helpful to know what supramolecular synthons are available and to understand the forces that make these synthons stick to one another. In this review we focus on σ-hole and π-hole interactions. A σ- or π-hole can be seen as positive electrostatic potential on unpopulated σ* or π(*) orbitals, which are thus capable of interacting with some electron dense region. A σ-hole is typically located along the vector of a covalent bond such as XH or XHlg (X=any atom, Hlg=halogen), which are respectively known as hydrogen and halogen bond donors. Only recently it has become clear that σ-holes can also be found along a covalent bond with chalcogen (XCh), pnictogen (XPn) and tetrel (XTr) atoms. Interactions with these synthons are named chalcogen, pnigtogen and tetrel interactions. A π-hole is typically located perpendicular to the molecular framework of diatomic π-systems such as carbonyls, or conjugated π-systems such as hexafluorobenzene. Anion–π and lone-pair–π interactions are examples of named π-hole interactions between conjugated π-systems and anions or lone-pair electrons respectively. While the above nomenclature indicates the distinct chemical identity of the supramolecular synthon acting as Lewis acid, it is worth stressing that the underlying physics is very similar. This implies that interactions that are now not so well-established might turn out to be equally useful as conventional hydrogen and halogen bonds. In summary, we describe the physical nature of σ- and π-hole interactions, present a selection of inquiries that utilise σ- and π-holes, and give an overview of analyses of structural databases (CSD/PDB) that demonstrate how prevalent these interactions already are in solid-state structures.

The Bright Future of Unconventional σ/π-Hole Interactions

We report evidence of the favorable noncovalent interaction between a covalently bonded atom of Group 18 (known as noble gases or aerogens) and a negative site, for example, a lone pair of a Lewis base or an anion. It involves a region of positive electrostatic potential (σ-hole), therefore it is a totally new and unexplored σ-hole-based interaction, namely aerogen bonding. We demonstrate for the first time the existence of σ-hole regions in aerogen derivatives by means of high-level ab initio calculations. In addition, several crystal structures retrieved from the Cambridge Structural Database (CSD) give reliability to the calculations. Energetically, aerogen bonds are comparable to hydrogen bonds and other σ-hole-based interactions but less directional. They are expected to be important in xenon chemistry.

Aerogen Bonding Interaction: A New Supramolecular Force?

In this article, we report a comprehensive theoretical study of halogen, chalcogen, and pnicogen bonding interactions using a large set of pure and hybrid functionals and some ab initio methods. We have observed that the pure and some hybrid functionals largely overestimate the interaction energies when the donor atom is anionic (Cl– or Br–), especially in the halogen bonding complexes. To evaluate the reliability of the different DFT (BP86, BP86-D3, BLYP, BLYP-D3, B3LYP, B97-D, B97-D3, PBE0, HSE06, APFD, and M06-2X) and ab initio (MP2, RI-MP2, and HF) methods, we have compared the binding energies and equilibrium distances to those obtained using the CCSD(T)/aug-cc-pVTZ level of theory, as reference. The addition of the latest available correction for dispersion (D3) to pure functionals is not recommended for the calculation of halogen, chalcogen, and pnicogen complexes with anions, since it further contributes to the overestimation of the binding energies. In addition, in chalcogen bonding interactions,...

On the Reliability of Pure and Hybrid DFT Methods for the Evaluation of Halogen, Chalcogen, and Pnicogen Bonds Involving Anionic and Neutral Electron Donors.

In this manuscript we analyze the Cambridge Structural Database (CSD) to compare the relative importance of halogen, chalcogen and pnicogen bonding. The three interactions can be explained in terms of electrostatic effects, considering the halogen, chalcogen or pnicogen as a Lewis acid due to the presence of a sigma hole (σ-hole). We have studied the behaviour of the three interactions considering two types of Lewis bases: amines and arenes. Combining the CSD search and a comprehensive theoretical study (DFT-D3) we conclude that the halogen bonding interaction is the energetically most favourable when the electron donor is an amine. In contrast, the pnicogen bond is the most favourable if the Lewis base is benzene (pnicogen–π interaction).

Antonio Bauzá

Papers

Tetrel‐Bonding Interaction: Rediscovered Supramolecular Force?

The Bright Future of Unconventional σ/π-Hole Interactions

Aerogen Bonding Interaction: A New Supramolecular Force?

On the Reliability of Pure and Hybrid DFT Methods for the Evaluation of Halogen, Chalcogen, and Pnicogen Bonds Involving Anionic and Neutral Electron Donors.

Halogen bonding versus chalcogen and pnicogen bonding: a combined Cambridge structural database and theoretical study