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Symmetry
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Reactions, Structures, and Properties of Small Clusters: Experiments and Theory
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Reactions, Structures, and Properties of Small Clusters: Experiments and Theory

A special issue of Symmetry (ISSN 2073-8994). This special issue belongs to the section "Chemistry: Symmetry/Asymmetry".

Deadline for manuscript submissions: closed (31 December 2022) | Viewed by 8927

Special Issue Editor

Dr. Federico Palazzetti

E-Mail Website
Guest Editor
Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, Perugia, Italy
Interests: physical chemistry; theoretical chemistry; molecular dynamics; molecular beams
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Clusters are aggregates of atoms or molecules whose size ranges from a few units up to hundreds of millions of constituents. According to the nature of the components, clusters can be bound by weak interactions of the order of less than 1 kJ/mol, such as van der Waals forces or hydrogen bonds, or by strong interactions of the order of hundreds kJ/mol, as in the case of covalent bonds. Clusters represent a link between the bulk matter and the single molecule. They exhibit peculiar physical and chemical properties that differ remarkably from those that characterize the bulk matter. Such deviations from the bulk system behavior increase as the number of components decreases. For small clusters, the variation of the properties becomes strongly dependent on the number of constituents, until resembling the behavior of the molecular matter.

This Special Issue is addressed to all the research groups involved in the development of theoretical models for the study of reaction mechanisms of small clusters and issues related to symmetry properties and chirality, with special emphasis on reaction dynamics, structure, weak interactions, thermodynamics, kinetics, and innovative applications.

Dr. Federico Palazzetti
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Symmetry is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

Reaction dynamics;

Reaction mechanisms;

Group theory;

Symmetry properties;

Chirality;

Photochemistry;

Photodissociation dynamics;

Phase transitions;

Trajectory simulations;

Rare-gas clusters;

Non-covalent interactions;

Small metal clusters;

Small molecular clusters;

Small ionic clusters

Published Papers (5 papers)

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Research

11 pages, 2029 KiB  
Article
Molecular Blueprinting by Word Processing
by Savino Longo
Symmetry 2023, 15(2), 357; https://doi.org/10.3390/sym15020357 - 29 Jan 2023
Cited by 2 | Viewed by 1640
Abstract
In this work, computer-assisted writing techniques for linear expressions of the structure of polycyclic molecules, branched molecules and clusters, based on formal languages, are tested. The techniques used only require the ability to process written texts, even just using a text editor, and [...] Read more.
In this work, computer-assisted writing techniques for linear expressions of the structure of polycyclic molecules, branched molecules and clusters, based on formal languages, are tested. The techniques used only require the ability to process written texts, even just using a text editor, and one of the many available molecular drawing/optimization programs that accept input in the form of a SMILES string. A few specific syntactic operators acting on strings are characterized in terms of their effect on the corresponding structure, and although they are simply examples, they are already capable of producing non-trivial structures. The aim of this work is to encourage experiments that may lead to potentially interesting molecular schemata, in view of their symmetry and stereochemistry, as revealed by optimization, and to develop insight into the connection between formal expressions and structures. Given the simplicity and availability of the required tools, it can also be useful for education. Full article
(This article belongs to the Special Issue Reactions, Structures, and Properties of Small Clusters: Experiments and Theory)
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11 pages, 1743 KiB  
Article
A Neutral Heteroleptic Molybdenum Cluster trans-[{Mo6I8}(py)2I4]
by Margarita V. Marchuk, Yuri A. Vorotnikov, Anton A. Ivanov, Ilia V. Eltsov, Natalia V. Kuratieva and Michael A. Shestopalov
Symmetry 2022, 14(10), 2117; https://doi.org/10.3390/sym14102117 - 12 Oct 2022
Cited by 7 | Viewed by 1095
Abstract
Despite that the chemistry of octahedral cluster complexes has been actively developed recently, there are still a lot of unexplored areas. For example, to date, only a few halide M6-clusters with N-heterocycles are known. Here, we obtained an apically heteroleptic octahedral [...] Read more.
Despite that the chemistry of octahedral cluster complexes has been actively developed recently, there are still a lot of unexplored areas. For example, to date, only a few halide M6-clusters with N-heterocycles are known. Here, we obtained an apically heteroleptic octahedral iodide molybdenum cluster complex with pyridine ligands—trans-[{Mo6I8}(py)2I4] by the direct substitution of iodide apical ligands of [{Mo6I8}I6]2– in a pyridine solution. The compound co-crystalized with a monosubstituted form [{Mo6I8}(py)I5]– in the ratio of 1:4, and thus, can be described by the formula (pyH)0.2[{Mo6I8}(py)1.8I4.2]·1.8py. The composition was studied using XRPD, elemental analyses, and 1H-NMR and IR spectroscopies. According to the absorption and luminescence data, the partial substitution of apical ligands weakly affects optical properties. Full article
(This article belongs to the Special Issue Reactions, Structures, and Properties of Small Clusters: Experiments and Theory)
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17 pages, 2953 KiB  
Article
Conformer Selection by Electrostatic Hexapoles: A Theoretical Study on 1-Chloroethanol and 2-Chloroethanol
by Concetta Caglioti, Masaaki Nakamura, Dock-Chil Che, Po-Yu Tsai and Federico Palazzetti
Symmetry 2022, 14(2), 317; https://doi.org/10.3390/sym14020317 - 4 Feb 2022
Cited by 2 | Viewed by 1612
Abstract
The electrostatic hexapole is a versatile device that has been used for many years in gas-phase experiments. Its inhomogeneous electric field has been employed for many purposes such as the selection of rotational states, the selection of clusters, the focusing of molecular beams, [...] Read more.
The electrostatic hexapole is a versatile device that has been used for many years in gas-phase experiments. Its inhomogeneous electric field has been employed for many purposes such as the selection of rotational states, the selection of clusters, the focusing of molecular beams, and molecular alignment as a precursor for molecular orientation. In the last few years, the hexapolar electric field has been demonstrated to be able to control the conformer composition of molecular beams. The key point is that conformers, where the component of the permanent electric dipole moment with respect to the largest of the principal axes of inertia is close to zero, require more intense hexapolar electric fields to be focused with respect to the other conformers. Here, we simulated the focusing curves of the conformers of 1-chloroethanol and 2-chloroethanol under hypothetical beam conditions, identical for all conformers, in a hypothetical and realistic experimental setup with three different hexapole lengths: 0.5, 1, and 2 m. The objective was to characterize this selection process to set up collision experiments on conformer-selected beams that provide information on the van der Waals clusters formed in collision processes. Full article
(This article belongs to the Special Issue Reactions, Structures, and Properties of Small Clusters: Experiments and Theory)
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12 pages, 3371 KiB  
Article
Thermally Controlled Synthesis of Octahedral Rhenium Clusters with 4,4′-Bipyridine and CN− Apical Ligands
by Anton A. Ulantikov, Taisiya S. Sukhikh, Evgeniy N. Gribov, Natalia V. Maltseva, Konstantin A. Brylev, Yuri V. Mironov and Yakov M. Gayfulin
Symmetry 2021, 13(11), 2187; https://doi.org/10.3390/sym13112187 - 16 Nov 2021
Cited by 5 | Viewed by 1426
Abstract
The selective preparation, structural and spectroscopic study of two new rhenium cluster complexes trans-[Re6S8(bpy)4(CN)2] and trans-[Re6S8(bpy)2(CN)4]2− (bpy = 4,4′-bipyridine) obtained by reactions of corresponding [...] Read more.
The selective preparation, structural and spectroscopic study of two new rhenium cluster complexes trans-[Re6S8(bpy)4(CN)2] and trans-[Re6S8(bpy)2(CN)4]2− (bpy = 4,4′-bipyridine) obtained by reactions of corresponding hexarhenium cyanohalides with molten bpy are reported. The complexes were crystallized as solvates, displaying supramolecular structures based on cluster units linked by numerous weak interactions with bpy molecules. The molecular compound trans-[Re6S8(bpy)4(CN)2] (1) is insoluble in water and common organic solvents, while the ionic compound trans-Cs1.7K0.3[Re6S8(bpy)2(CN)4] (2) is somewhat soluble in DMSO, DMF and N-methylpyrrolidone. The presence of the redox-active ligand bpy leads to the occurrence of multi-electron reduction transitions in a solution of 2 at moderate potential values. The ambidentate CN− ligand is the secondary functional group, which has potential for the synthesis of coordination polymers based on the new cluster complexes. In addition, both new compounds show a weak red luminescence, which is characteristic of complexes with a {Re6S8}2+ cluster core. Full article
(This article belongs to the Special Issue Reactions, Structures, and Properties of Small Clusters: Experiments and Theory)
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9 pages, 1489 KiB  
Article
Synthesis and Characterisation of a Boron-Rich Symmetric Triazine Bearing a Hypoxia-Targeting Nitroimidazole Moiety
by Tobias Hartwig Bünning, Luigi Panza, Abdel Kareem Azab, Barbara Muz, Silvia Fallarini and Daniela Imperio
Symmetry 2021, 13(2), 202; https://doi.org/10.3390/sym13020202 - 27 Jan 2021
Viewed by 2268
Abstract
Boron Neutron Capture Therapy (BNCT) is a binary therapy that promises to be suitable in treating many non-curable cancers. To that, the discovery of new boron compounds able to accumulate selectively in the tumour tissue is still required. Hypoxia, a deficiency of oxygen [...] Read more.
Boron Neutron Capture Therapy (BNCT) is a binary therapy that promises to be suitable in treating many non-curable cancers. To that, the discovery of new boron compounds able to accumulate selectively in the tumour tissue is still required. Hypoxia, a deficiency of oxygen in tumor tissue, is a great challenge in the conventional treatment of cancer, because hypoxic areas are resistant to conventional anticancer treatments. 2-Nitroimidazole derivatives are known to be hypoxia markers due to their enrichment by bioreduction in hypoxic cells. In the present work, 2-nitroimidazole was chosen as the starting point for the synthesis of a new boron-containing compound based on a 1,3,5-triazine skeleton. Two o-carborane moieties were inserted to achieve a high ratio of boron on the molecular weight, exploiting a short PEG spacer to enhance the polarity of the compound and outdistance the active part from the core. The compound showed no toxicity on normal human primary fibroblasts, while it showed noteworthy toxicity in multiple myeloma cells together with a consistent intracellular boron accumulation. Full article
(This article belongs to the Special Issue Reactions, Structures, and Properties of Small Clusters: Experiments and Theory)
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