Tetrel bond affects the self-assembly of acetylcholine and its analogues and is an ancillary interaction in protein binding.

The -N+(CH3)3 residue is present in acetylcholine (ACh) and in many of its analogues which are used as selective ACh agonist or antagonists for human therapy.  The X-ray structures of four ACh derivatives show the presence of short and linear contacts between the C atoms of -N+(CH3)3 groups and lone pair possessing atoms.  These contacts can be rationalized as tetrel bonds (TtBs) thanks to their geometric features.  Interrogation of the Protein Data Bank suggests that similar -N+‒C···nucleophile contacts affect the details of the binding of ACh and its derivatives to proteins.  Quantum theory of atoms in molecules, noncovalent interaction plot, and natural bond orbital analyses consistently confirm that the -N+‒C···nucleophile contacts observed in small molecule crystals and in substrate/protein complexes are attractive in nature and can be rationalized as TtBs.  TtBs involving methyl groups of the -N+(CH3)3 moiety can be proposed as a new item in the palette of interactions allowing the compounds containing this pharmacophoric unit to bind to their target protein and/or to express their biological/pharmacological properties.

Osme Bond: Geometric and Energetic Features in the Adducts between OsO4 and Lewis Bases.

Adducts between OsO4 and Lewis bases exert a role in important oxidation processes such as epoxidation and dihydroxylation. It has been shown that the attractive interaction driving the formation of these adducts is a σ-hole bond involving the metal as the electrophilic species; the term Osme Bond (OmB) was proposed for designating it. Here some new adducts between OsO4 and various bases have been characterized through single crystal x-ray diffraction (XRD) and computational studies (density functional theory, DFT), confirming the existence of a robust correlation between σ-hole interaction energy and deformation of the tetrahedral geometry of OsO4. Also, some adducts formed by RuO4 with nucleophiles were investigated computationally.

Chalcogen and Hydrogen Bond Team up in Driving Anion⋠⋠⋠Anion Self-Assembly.

H-selenite anions (HSeO3 - ) form in the solid unprecedented anionic supramolecular chains wherein single units are assembled via alternating short Se⋅⋅⋅O and H⋅⋅⋅O contacts. Crystallographic analyses and computational studies (the quantum theory of "atoms-in-molecules", QTAIM, and the noncovalent interaction plot, NCIPlot) consistently prove the attractive nature of these chalcogen bonds (ChBs) and hydrogen honds (HBs), the Janus-type character of HSeO3 - anions which act as both donors and acceptors of ChB and HB, and the possible stability of anion dimers in solution. The effectiveness of the ChBs herein described may lead to consider the HSeO3 - moiety as a new entry in the toolbox of crystal engineering based on ChB.

Non-covalent matere bonds in perrhenates probed via ultrahigh field rhenium-185/187 NMR and zero-field NQR spectroscopy.

Matere bonds (MaB) to rhenium in a set of organic perrhenates are probed via185/187Re solid-state NMR in applied magnetic fields of up to 35.2 T, and via185/187Re NQR. 185/187Re quadrupolar couplings distinguish between MaB samples and control samples, and their precise values are governed by shear strain of the ReO4- anions.

Geminal Charge-Assisted Tetrel Bonds in Bis-Pyridinium Methylene Salts.

C(sp3) atoms are known to act as electrophilic sites in self-assembly processes, and in all cases reported till now, they form only one interaction with nucleophiles; that is, they function as monodentate tetrel bond donors. This manuscript reports experimental (X-ray structural analysis) and theoretical evidence (DFT calculations), proving that the methylene carbon in bis-pyridinium methylene salts establishes two short and directional C(sp3)···anion interactions; that is, they function as bidentate tetrel bond donors.

Erythronium Bonds: Noncovalent Interactions Involving Group†5 Elements as Electron-Density Acceptors.

Analyses of the Cambridge Structural Database and theoretical calculations (PBE0-D3/def2-TZVP level, atoms-in-molecules, natural bond orbital studies) prove the formation of net attractive noncovalent interactions between group 5 elements and electron-rich atoms (neutral or anionic). These kinds of bonding are markedly different from coordination bonds formed by the same elements and possess the distinctive features of σ-hole interactions. The term erythronium bond is proposed to denote these bonds. X-ray structures of vanadate-dependent bromoperoxidases show that these interactions are present also in biological systems.

Halogen Bonding Assembles Anion⋠⋠⋠Anion Architectures in Non-centrosymmetric Iodate and Bromate Crystals.

Single crystal X-ray diffraction of iodate and bromate salts shows that the I and Br atoms in IO3 - and BrO3 - anions form short and linear O-I/Br⋅⋅⋅O contacts with the O atoms of nearby anions. Non-centrosymmetric systems are formed wherein anions are orderly aligned into supramolecular 1D and 2D networks. Theoretical evidences, namely the outcome of QTAIM and NCIplot studies, prove the attractive nature of these contacts and the ability of iodate and bromate anions to act as robust halogen bond (HaB) donors. The HaB is proposed as a general and effective assisting tool to control the architecture of acentric iodate salts.

Group-10 π-hole⋯dz2[MII] interactions: a theoretical study of model systems inspired by CSD structures.

In recent years Pd(II) and Pt(II) cases have been reported wherein metals in square planar complexes were used as nucleophilic partners to construct supramolecular assemblies with electrophilic molecules like σ-hole and π-hole donors. The formation of such assemblies is based on the nucleophilicity and accessibility of the dz2 orbital (in group-10 elements) in the square-planar complexes. This opens new avenues in inorganic chemistry and crystal engineering as it enriches the current toolbox of noncovalent interactions and supramolecular synthons thus allowing the design of new types of architectures in the solid state. This manuscript reports a comprehensive theoretical study characterizing π-hole⋯dz2[MII] (M = group 10 element) interactions from an energetic point of view. Several computational tools based on the topology of the electron density are used. Examined systems had been identified by considering structures in the Cambridge Structural Database where this interaction was used to construct supramolecular assemblies. Several aromatic rings have been used, varying from π-basic to π-acid rings by adjusting the number of fluorine substituents. Moreover, the influence of metal⋯metal interactions on the nucleophilicity of the dz2 orbital has been studied using MEP surface analysis. The π-hole energies are moderately strong (from -5 to -10 kcal mol-1) and the crucial role of dispersion forces is revealed.

σ-Hole interactions in organometallic catalysts: the case of methyltrioxorhenium(VII).

Methyltrioxorhenium(VII) (MTO) is a widely employed catalyst for metathesis, olefination, and most importantly, oxidation reactions. It is often preferred to other oxometal complexes due to its stability in air and higher efficiency. The seminal papers of K. B. Sharpless showed that when pyridine derivatives are used as co-catalysts, MTO-catalyzed olefin epoxidation with H2O2 as oxidant, a particularly useful reaction, is accelerated, with pyridine speeding up catalytic turnover and increasing the lifetime of MTO under the reaction conditions. In this paper, combined experimental and theoretical results show that the occurrence of σ-hole interactions in catalytic systems extends to MTO. Four crystalline adducts between MTO and aliphatic and heteroaromatic bases are obtained, and their X-ray analyses display short Re⋯N/O contacts opposite to both O-Re and C-Re covalent bonds with geometries consistent with σ-hole interactions. Computational analyses support the attractive nature of these close contacts and confirm that their features are typical of σ-hole interactions. The understanding of the nature of Re⋯N/O interactions may help to optimize the ligand-acceleration effect of pyridine in the epoxidation of olefins under MTO catalysis.

Periodate anions as a halogen bond donor: formation of anion⋯anion dimers and other adducts.

Single crystal X-ray analyses show that iodine in pyridinium periodates acts as a halogen bond (HaB) donor forming short and almost linear contacts with neutral and anionic electron donors. A combination of QTAIM and NCIplot computational tools proves the attractive nature of these contacts.

Molecular Electrostatic Potential and Noncovalent Interactions in Derivatives of Group 8 Elements.

This communication reports experimental and theoretical evidences of σ-hole interactions in adducts between nitrogen or oxygen nucleophiles and tetroxides of osmium or other group 8 elements. Cocrystals between pyridine or pyridine N-oxide derivatives and osmium tetroxide are characterized through various techniques and rationalized as σ-hole interactions using DFT calculations and several other computational tools. We propose the term "osme bond" (OmB, Om=Fe, Ru, Os, (Hs)) for naming the noncovalent interactions wherein group 8 elements have the role of the electrophile. The word osme is the transcription of ὀσµÎ®, the ancient Greek word for smell that was used to name the heaviest group 8 element in relation to the smoky odor of its tetroxide.

Symptom assessment of patients with advanced cancer and AIDS and their family caregivers: the results of a quality-of-life pilot study.

This longitudinal pilot study examined differences in demographic characteristics of 101 patients with advanced illness (cancer, AIDS) and 81 Family caregivers, evaluated the reliability of the Memorial Symptom Assessment Scale for these patients and their family caregivers; obtained preliminary data regarding similarities or differences in the symptom experience oF these patients and their family caregivers and changes in symptoms over time; and identified demographic variables that may be potential covariates related to the symptom experience. All demographic variables were significantly different for patients with advanced cancer and AIDS, and their symptom experience is similar only with regard to psychologic symptoms; however, based on the Memorial Symptom Assessment Scale, cancer and AIDS patients and their family caregivers have similar symptom experiences, indicating the need for palliative care for both patients and family. Further research is needed to establish the reliability of the Memorial Symptom Assessment Scale for use with family caregivers.

Quality of life of patients with advanced cancer and acquired immune deficiency syndrome and their family caregivers.

BACKGROUND: Although definitions of palliative care include quality of life as a central concern, little research has been published about both the quality of life of patients with advanced illness and their family members, and particularly the changes in their quality of life over time. OBJECTIVES: The aims of this prospective longitudinal pilot study were to: (1) establish the reliability of multidimensional quality of life instruments based on patients with acquired immune deficiency syndrome (AIDS) and patients with cancer and caregivers; (2) identify differences in quality of life between patients with advanced AIDS and cancer, and their family caregivers with consideration of mortality, attrition, and compliance rates; and (3) examine differences in demographic variables and their potential confounding effect when measuring quality of life. METHODS: The sample included 101 patients with advanced illness (63 patients with advanced AIDS and 38 with advanced cancer) and 81 family caregivers (43 caregivers for patients with AIDS and 38 caregivers for patients with cancer). Data collection involved the monthly completion of the McGill Quality of Life Questionnaire (MQOL) for patients, and the Quality of Life Scale (QLS) for family caregivers. RESULTS: Reliability of the MQOL and QLS were established for patients with AIDS and patients with cancer and caregivers. Based on the MQOL, patients with advanced AIDS reported a lower total quality of life, and lower psychological quality of life, and a higher physical quality of life compared to patients with advanced cancer. There were no significant differences between patient groups on the one-item physical well-being subscale, or the existential well-being, and support subscales. Based on the QLS, AIDS caregivers reported greater overall quality of life, greater psychological well-being, and greater spiritual well-be- ing than cancer caregivers. There were no significant differences between AIDS and cancer caregivers with respect to physical or social well-being. From baseline entry into the study to third month of participation, there were no significant changes in total quality of life scores for patient or caregiver groups, although trends indicated a moderately high total quality of life over time for all patient and caregiver groups. Fourteen of 63 (22%) patients with AIDS patients died, while 19 of 38 (50%) patients with advanced cancer died after enrollment. Forty-six of 63 (73%) patients with advanced AIDS withdrew for various reasons other than death at some point during the 12 month time frame of the study, while 15 of 38 (39%) patients with advanced cancer withdrew. There were significant differences on all demographic variables for patients with advanced cancer and AIDS. Only religious affiliation was significantly related to quality of life for patients with AIDS, while gender was the only variable associated with quality of life for patients with cancer. There were significant differences on all demographic variables between caregivers with the exception of gender and living arrangements. Only the relationship between patients and caregivers and marital status were significantly associated with quality of life for cancer caregivers. CONCLUSIONS: In palliative care research, the challenge is to design studies that will capture changes in the domains of quality of life over time, yet will minimize participant burden and subsequent attrition rates. By measuring quality of life as an outcome variable in palliative care, health professionals can identify changes in the domains of quality of life over time for various patient populations and their family caregivers, and respond with appropriate interventions, which promote or maintain their quality of life even as death approaches.

Spiritual well-being as a dimension of quality of life for patients with advanced cancer and AIDS and their family caregivers: results of a longitudinal study.

Based on a longitudinal, quality-of-life study, this article presents pilot data regarding the spiritual well-being of patients with advanced cancer or AIDS and their family caregivers. Data include similarities and differences between the patient and caregiver populations and patient/family caregiver dyads as well as trends with regard to changes in spiritual well-being during the illness and dying process. The reliability of the Spiritual Well-Being Scale was examined for patient and caregiver groups, as was the relationship between selected demographic variables and spiritual well-being. Implications for practice are discussed.

Recruitment and retention in a longitudinal palliative care study.

A longitudinal feasibility study regarding quality of life and interventions for patients with advanced cancer or AIDS and their family caregivers was conducted to determine issues related to their recruitment and retention and to obtain pilot data relevant to the development of a larger study. At the completion of the study, a focus group consisting of the members of the palliative care research team was convened to identify barriers to and facilitators of the research process based on their research experience. The purpose of this article is to (1) describe recruitment, mortality rates, attrition rates, and compliance with data collection of patients and family caregivers experiencing an advanced illness and to (2) examine the researchers' perspectives regarding barriers to and facilitators of the research process that relate to patients and family caregivers, institutions, the data collection process, and their personal experiences. Implications for palliative care research are discussed.