C2v Symmetry Research Articles

Rotational Spectroscopy Probes Lone Pair···π-Hole Interactions in Hexafluorobenzene-Tertiary Alkylamines Complexes.

We employed microwave spectroscopy to investigate the 1:1 complexes of hexafluorobenzene with trimethylamine and quinuclidine, respectively. These complexes exhibit a C3v symmetry and are stabilized by nitrogen lone pair···π-hole interactions along the C3 axes. The N···π-center distances were determined to be 3.110(1) and 3.040(2) Å, respectively, which are shorter than that of hexafluorobenzene-ammonia at 3.2685(3) Å. Additionally, the strength of the intermolecular interaction increases with cluster size. While it was initially expected that the electron-donating effect of alkyl groups was responsible for changing the N···π interaction, the symmetry-adapted perturbation theory analysis revealed that, from hexafluorobenzene-ammonia to both hexafluorobenzene-alkylamines, electrostatic interaction actually decreases while dispersion interaction increases and becomes dominant. Interestingly, dispersion interaction decreases while electrostatic interaction increases from C6F6-N(CH3)3 to C6F6-NC7H13. The splitting pattern of the spectra indicates hexafluorobenzene rotates freely relative to its partners along the axis of the N···π-hole interactions.

Unique Huygens-Fresnel electromagnetic transportation of chiral Dirac wavelet in topological photonic crystal

Light propagates in various ways depending on environment, including uniform medium, surface/interface and photonic crystals, which appears ubiquitously in daily life and has been exploited for advanced optics technology. We unveiled that a topological photonic crystal exhibits unique electromagnetic (EM) transport properties originating from the Dirac frequency dispersion and multicomponent spinor eigenmodes. Measuring precisely local Poynting vectors in microstrips of honeycomb structure where optics topology emerges upon a band gap opening in the Dirac dispersion and a p-d band inversion induced by a Kekulé-type distortion respecting C6v symmetry, we showed that a chiral wavelet induces a global EM transportation circulating in the direction counter to the source, which is intimately related to the topological band gap specified by a negative Dirac mass. This brand-new Huygens-Fresnel phenomenon can be considered as the counterpart of negative refraction of EM plane waves associated with upwardly convex dispersions of photonic crystals, and our present finding is expected to open a new window for photonic innovations.

Crystal-field analysis and models of Eu-emission centers with C3v symmetry in insitu Eu- and Mg-codoping GaN layers

Gallium nitride active layers co-doped in situ with magnesium and europium, GaN(Mg):Eu, show strong red photoluminescence (PL), promising for red light emitting diode (LED) application (Eu@621 nm). Polarized PL lines excited by either above or below band-gap energy for the GaN(Mg):Eu layers are assigned to the 5D0→7FJ (J = 0, 1, 2) transitions lines from several Eu centers with C3v symmetry, which consist of single line, double lines and triple lines related to splitting of 7FJ (J = 0, 1, 2) by the C3v crystal-field, respectively. Cascade luminescence line-pattern of the 5D1→7FJ (J = 0, 1, 2) transitions is a complete replica of the PL line-pattern and gives evidence of the correct assignment of the polarized PL lines. Crystal-field splitting and Zeeman splitting of the PL lines have been analysed using the C3v crystal-field equivalent operator Hamiltonian. Structural Eu models with the C3v symmetry have been proposed on the basis of the analysis: the dominant Eu center is an Eu complex with defect-free perfect surrounding: the minor Eu centers are Eu complexes accompanied by nitrogen vacancies with different charge states on the c-axis in the closest vicinity of Eu. An important role of Mg atoms in the GaN(Mg):Eu active layers has been proposed to suppress creation of gallium vacancies, giving rise to enhancement of the PL emitted from the defect-free Eu centers.

Comparative rotatory power of bent and twisted polyynes.

Linear polyynes of the formula C18 H2 (symmetry D∞h ) were bent in silico by progressively introducing CCC angles less than 180°. The bent structures (symmetry C2v ) were then twisted by introducing torsion angles across the CCCC segments by as much as 60°. The gyration tensors of these 19 structures (linear, bent, and twisted) were computed by linear response methods. Bending is massively generative of optical activity in oriented structures, even achiral structures, whereas twisting in conjunction with bending, serves to linearize the molecules and diminish maximally observable optical activity. This computational exercise is intended to unbind the infelicitous linkage of optical activity and chirality, which is only meaningful in isotropic media. Although bent structures are not optically active in solution-the spatial average of the optical activity is necessarily zero-solution measurements that deliver the spatial averages are a special class of measurements, albeit the overwhelmingly most common chiroptical measurements, that prejudice our common understanding of how π-conjugated structures generate gyration. Bending is far more effective than twisting at generating optical activity along some directions for oriented structures. The respective contributions from the transition electric dipole-magnetic dipole polarizability and the transition electric dipole-electric quadrupole polarizability are compared.

Collisional excitation of methyl (iso)cyanide by He atoms: rate coefficients and isomerism effects

ABSTRACT Among all closed-shell species observed in molecular clouds, molecules with C3v symmetry play a crucial role, as their rotational spectroscopy allows them to behave as a gas thermometer. In the interstellar medium, methyl cyanide (CH3CN) is the second most abundant of those (after ammonia, NH3). Its isomer, methyl isocyanide (CH3NC), is less abundant but has been detected in many astrophysical sources. In order to assess their absolute and relative abundances, it is essential to understand their collisional excitation properties. This paper reports the calculation of rate coefficients for rotational excitation of CH3CN and CH3NC molecules with He atoms, from low (5 K) to moderate (100 K) temperatures. We include the first 74 and 66 rotational states of both para and ortho symmetries of CH3CN and CH3NC, respectively. A propensity for Δj = 2 transitions is observed in the case of CH3CN-He collisions, whereas in the case of CH3NC-He a propensity for Δj = 1 is observed for transitions involving low values of j and at low temperatures, a propensity for Δj = 2 is observed for higher values of j and at high temperatures. A comparison of rate coefficients shows differences up to a factor of 3, depending on temperature and on the ortho/para symmetries for dominant transitions. This confirms the importance of having specific collisional data for each isomer. We also examined the effect of these new rates on the CH3CN and CH3NC excitation in molecular clouds by performing radiative transfer calculations of the excitation and brightness temperatures for several detected lines.

Five Bonds to Carbon through Tri-Coordination in 
 Al3C3−/0

Here, five bonds to carbon through tri-coordination are theoretically established in the global minimum energy isomers of Al3C3− anion (1a) and Al3C3 neutral (1n) for the first time. Various isomers of Al3C3−/0 are theoretically identified using density functional theory at the PBE0-D3/def2-TZVP level. Chemical bonding features are thoroughly analyzed for these two isomers (1a and 1n) with different bonding and topological quantum chemical tools, such as adaptive natural density partitioning (AdNDP), Wiberg Bond Indices (WBIs), nucleus-independent chemical shifts (NICS), and atoms in molecules (AIM) analyses. The structure of isomer 1a is planar with C2v symmetry, whereas its neutral counterpart 1n is non-planar with C2 symmetry, in which its terminal aluminum atoms are out of the plane. The central allenic carbon atom of isomers 1a and 1n exhibits tri-coordination and thus makes it a case of five bonds to carbon, which is confirmed through their total bond order as observed in WBI. Both the isomers show σ- and π-aromaticity and are predicted with the NICS and AdNDP analyses. Further, the results of ab initio molecular dynamics simulations reveal their kinetic stability at room temperature; thus, they are experimentally viable systems.

Exploiting Molecular Symmetry to Quantitatively Map the Excited-State Landscape of Iron-Sulfur Clusters.

Cuboidal [Fe4S4] clusters are ubiquitous cofactors in biological redox chemistry. In the [Fe4S4]1+ state, pairwise spin coupling gives rise to six arrangements of the Fe valences ("valence isomers") among the four Fe centers. Because of the magnetic complexity of these systems, it has been challenging to understand how a protein's active site dictates both the arrangement of the valences in the ground state as well as the population of excited-state valence isomers. Here, we show that the ground-state valence isomer landscape can be simplified from a six-level system in an asymmetric protein environment to a two-level system by studying the problem in synthetic [Fe4S4]1+ clusters with solution C3v symmetry. This simplification allows for the energy differences between valence isomers to be quantified (in some cases with a resolution of <0.1 kcal/mol) by simultaneously fitting the VT NMR and solution magnetic moment data. Using this fitting protocol, we map the excited-state landscape for a range of clusters of the form [(SIMes)3Fe4S4-X/L]n, (SIMes = 1,3-dimesityl-imidazol-4,5-dihydro-2-ylidene; n = 0 for anionic, X-type ligands and n = +1 for neutral, L-type ligands) and find that a single ligand substitution can alter the relative ground-state energies of valence isomers by at least 103 cm-1. On this basis, we suggest that one result of "non-canonical" amino acid ligation in Fe-S proteins is the redistribution of the valence electrons in the manifold of thermally populated excited states.

Tuning the van Hove singularities in monolayer PbBiI via C3v symmetry breaking

Various filling fractions of the van Hove singularities (vHs) in the vicinity of the Fermi energy give rise to exotic phenomena. Here, we tune vHs in a new family member of quantum spin Hall insulators PbBiI via two mechanisms of C3v symmetry breaking; applying an in-plane magnetization exchange field and an inversion symmetry breaking field. Depending on the mechanism and dispersion direction of host electrons, we find Weyl nodes in the electronic band structure, and in turn, bare vHs deform away from the Fermi energy. Moreover, the number of vHs increases due to the reconstruction of the Fermi surface induced by the above mechanisms. Overall, we indeed propose two efficient mechanisms to tune/create vHs for various emergent applications in optoelectronics.

Merging a Negatively Curved Nanographene and a Carbon Nanoring

Two molecular nanocarbons result from merging a negatively curved nanographene and a carbon nanoring in two constitutional isomers of D2 and C2v symmetry, respectively. They were synthesized by attachment of C-shaped paraphenylene precursors to 2,11,18,27-tetrabromooctabenzo[8]circulene and the subsequent intramolecular Yamamoto coupling and reductive aromatization reactions. The flexible nature of octabenzo[8]circulene enabled two different ways of connection in the Yamamoto coupling reactions, leading to the two constitutional isomers. The D2 isomer is shaped like a figure eight, as revealed by X-ray crystallography, and is resolved into two enantiomers by chiral HPLC. The synthesis of the C2v isomer is regarded as a further step toward precision synthesis of carbon schwarzites through a bottom-up approach.

Emergence of Dirac cone in CsPbBr3 perovskite-based two-dimensional photonic crystals

In this paper, it has been proposed that all-inorganic perovskite materials can be used to design and fabricate two-dimensional (2D) photonic crystals. The theoretical study performed here shows that these perovskite-based 2D photonic crystals exhibit a Dirac cone dispersion. In this study, cesium lead bromide (CsPbBr3) having rectangular shapes of varying widths (50, 100, and 150 nm) and a fixed height of 300 nm are arranged in a regular manner with a lattice constant of 500 nm. The pattern of these photonic crystals exhibits C4v symmetry. It has been observed when these perovskite materials, arranged in a rectangular shape, are having a certain dimension; they display a Dirac cone dispersion at the centre of the Brillouin zone at a frequency close to peta-hertz. Further, these photonic crystals are used to manipulate the propagation of electromagnetic (EM) waves of frequency ∼4 × 1014 Hz. Near this frequency, the photonic crystals respond as a nearly zero refractive index material, which allows passing EM waves even in presence of an obstacle. This study can be expanded to design and fabricate two-dimensional photonic crystals based on various perovskite materials.

A spectroscopic approach to compare the quantum chemical calculations and experimental characteristics of some organic molecules; Benzene, Toluene, P-Xylene, P-Toluidine

In this study, first, Benzene molecule pretends as the starting point, and then methyl and amine groups were added to construct Benzene like molecules. After that, the change of the mentioned physical properties above was investigated. In addition, HOMO-LUMO, MEP, and character tables of these organic molecules were obtained, and the effect of group symmetry was investigated. Density functional theory calculations were used in this study to obtain vibrational and electronic spectra for the four ring molecules (Benzene, Toluene, p-Xylene, p-Toluidine) and optimized geometries of molecules were performed in these programs. It was concluded that the molecules belong to D6h, C2v, D2h and C2v symmetry point groups for Benzene, Toluene, p-Xylene, and p-Toluidine respectively. It is concluded that lowest C1-C2 bond was in Benzene and p-Xylene, and the highest C1-C2 bond was in Toluene. On the other hand, it was found out that many vibrational frequencies changed with the addition of subgroups. It was aimed to determine the interaction sites of each molecule. For this purpose, mulliken atomic charges, molecular electrostatic potential (MEP) surface map and quantum chemical properties such as hardness, softness, electronegativity, chemical potential, ionization potential, electrophilic index, dipole moment, electron affinity were calculated via Gaussian program.

Incorporating Highly Anisotropic Four-Coordinate Co(II) Ions within One-Dimensional Coordination Chains

Low-coordinate metallic ions have been well recognized for constructing good-performance single ion magnets (SIMs) due to their enhanced magnetic anisotropy; however, the incorporation of such specific ions into coordination polymers is still challenging. Here, we reported two new CoII coordination polymers, namely [Co(pdms)(bpe)]n (1) and {[Co(pdms)(tpb)]·H2O·tpb}n (2) (H2pdms = 1,2-bis(methanesulfonamido)benzene, bpe = 1,2-di(4-pyridyl)ethane, tpb = 1,2,4,5-tetra(4-pyridyl)benzene). Single crystal X-ray diffraction experiments indicated that the CoII centers in both 1 and 2 display a distorted tetrahedral geometry with quasi C2v symmetry and are linked into a one-dimensional (1D) zig-zag chain via the ditopic bridging ligand of bpe in 1 while a ribbon chain via the tetradentate linker of tpb in 2. Magnetic studies revealed the easy-axis magnetic anisotropy of the CoII ions with different zero-field splitting D of −19 cm–1 (1) and −33 cm–1 (2), likely due to the distinct changes in the Npy–Co–Npy bite angles (100.20° (1) vs. 93.90° (2)). Moreover, slow magnetic relaxation proceeded via different relaxation mechanisms under applied dc fields was observed, giving an effective energy barrier (Ueff) of 69.6 K for 1 and 76.6 K for 2, respectively. The ab initio calculations on both the polymers further confirmed the sign and magnitude of the ZFS parameters and nicely reproduced the experimental results. Our study demonstrated a great potential for applying the well-studied and highly anisotropic 4-coordinate metal ions within a coordination polymer, opening a viable means to tuning magnetic anisotropy via topological control.

Analog Quantum Valley–Hall and Quantum Spin Hall Plasmons in Graphene Metasurfaces with Low Point Group Symmetry

AbstractIn recent years, topological physics of classical waves in artificial crystals has become an emerging field of research. While Dirac cones and valley‐related physics are conventionally studied in these systems with C6v and C3v point‐group symmetries, here analog quantum valley Hall and quantum spin Hall plasmons in graphene metasurfaces with lower point‐group symmetries are explored. First, it is shown that a single‐layer graphene sheet with rectangle holes respecting to the C2v point group symmetry can host a mirror (σv) symmetry‐protected Dirac cone along the X–M edge of the Brillouin zone. Then we demonstrate that introducing further circular holes to the graphene sheet can break the mirror symmetry (i.e., reducing C2v symmetry to C1v) and thus gap out the Dirac cone, which allows us to explore the valley and layer‐pseudospin related topological plasmons in these graphene metasurfaces with low point group symmetry. Valley‐locking unidirectional propagations along the domain–wall interface of a single‐layer graphene metasurface and layer‐pseudospin converter in a double‐layer graphene metasurface are explicitly demonstrated for graphene plasmons in the THz range. This work provides a new design principle for exploring Dirac cones, valley, and pseudospin related physics using much lower point‐group symmetries.

Polarization-selective narrow band dual-toroidal-dipole resonances in a symmetry-broken dielectric tetramer metamaterial.

Here we propose a metasurface consisting of symmetry-broken dielectric tetramer arrays, which can generate polarization-selective dual-band toroidal dipole resonances (TDR) with ultra-narrow linewidth in the near-infrared region. We found, by breaking the C4v symmetry of the tetramer arrays, two narrow-band TDRs can be created with the linewidth reaching ∼ 1.5 nm. Multipolar decomposition of scattering power and electromagnetic field distribution calculations confirm the nature of TDRs. A 100% modulation depth in light absorption and selective field confinement has been demonstrated theoretically by simply changing the polarization orientation of the exciting light. Intriguingly, it is also found that absorption responses of TDRs on polarization angle follow the equation of Malus' law in this metasurface. Furthermore, the dual-band toroidal resonances are proposed to sense the birefringence of an anisotropic medium. Such polarization-tunable dual toroidal dipole resonances with ultra-narrow bandwidth offered by this structure may find potential applications in optical switching, storage, polarization detection, and light emitting devices.

A programmable auxetic metamaterial with tunable crystal symmetry

Artificially-structured materials with negative Poisson's ratio, also known as auxetics, have been the focus of numerous studies over the past few decades. In this paper, using a group-theory-based symmetry reduction approach, and based on a structure composed of rotating rigid triangles, we propose a new approach to designing auxetic metamaterials. These metamaterials can be fabricated by using a variety of active or smart structural members that undergo different deformations when subjected to external stimulations, e.g. by using temperature-sensitive members in a temperature-changing environment. Then, by applying controlled stimuli to the initial structure, we obtain desired symmetry-reduced structural configurations which facilitate the programmability of Poisson's ratio. In particular, to demonstrate this programmable metamaterial design approach, starting with an auxetic metamaterial with an initial C3v symmetry, we apply an external stimulus to reduce the symmetry of the initial structural configuration. The deformed configurations, which belong to the symmetry groups C3, CS, and C1, enable us to program the Poisson's ratio of the metamaterial. We derive theoretical expressions for the Poisson's ratio associated with different symmetries, which are subsequently verified by numerical studies and proof-of-concept Kirigami models. We anticipate that this approach to designing programmable structures will open up new avenues of research in metamaterial design.

Prediction of stable radon fluoride molecules and geometry optimization using first-principles calculations

Noble gases possess extremely low reactivity because their valence shells are closed. However, previous studies have suggested that these gases can form molecules when they combine with other elements with high electron affinity, such as fluorine. Radon is a naturally occurring radioactive noble gas, and the formation of radon-fluorine molecules is of significant interest owing to its potential application in future technologies that address environmental radioactivity. Nevertheless, because all isotopes of radon are radioactive and the longest radon half-life is only 3.82 days, experiments on radon chemistry have been limited. Here, we study the formation of radon molecules using first-principles calculations; additionally, possible compositions of radon fluorides are predicted using a crystal structure prediction approach. Similar to xenon fluorides, di-, tetra-, and hexafluorides are found to be stabilized. Coupled-cluster calculations reveal that RnF6 stabilizes with Oh point symmetry, unlike XeF6 with C3v symmetry. Moreover, we provide the vibrational spectra of our predicted radon fluorides as a reference. The molecular stability of radon di-, tetra-, and hexafluoride obtained through calculations may lead to advances in radon chemistry.

Electronic structure, cationic, and excited states of nitrogen-containing spiroborates.

This paper presents the results of the study of the electronic structure and cationic and excited states of three spiroborate complexes (2-acetylacetonato-1,3,2-benzodioxaborol, its NH- and NMe-derivatives) and three corresponding ligands (acetylacetone, 4-aminopent-3-en-2-one, and 4-methylaminopent-3-en-2-one).Materials based on spiroborates are used in medicine, for example, as a drug carrier. In industry, spiroborate anions are used in ionic liquids and as alternative high performance lubricants. Analysis of experimental and calculated data allowed determining the influence of functional groups on the parameters of the electronic structure and energy of electronic transitions. Compared to acetylacetone and its NH- and NMe-derivatives, the upper filled molecular orbitals of the corresponding spiroborates are stabilized at 0.4-1.7eV, which is due to the positive charge of the ligand due to the acceptor properties of the dioxyphenylene fragment. Among the studied compounds, when replacing the oxygen atom in the α-position with the NH- or NMe-group, a bathochromic shift of intense bands in the absorption spectra is observed, since the energy intervals between the orbitals of the π3 and π4 ligand are reduced. In addition, in a number of spiroborates, the violation of C2v symmetry when replacing an oxygen atom leads to the appearance of a low-intensity maximum in the long-wave part of the absorption spectrum, due to the π2X → π4 transition. Complexeswere studied by photoelectron spectroscopy, absorption spectroscopy, and high-level ab initio quantum chemical computations, including the algebraic diagrammatic construction method for the polarization propagator of the second order (ADC(2)), the outer-valence Green's function (OVGF), the density functional theory(DFT), the time-dependent density functional theory(TDDFT) andthe domain-based local pair natural orbital (EOM-DLPNO) methods.X-ray photoelectronic spectra of two spiroborates in the condensed state were measured using a two-chamber high-vacuum system MXPS XP (Omicron, Germany).UV-visible absorption spectra were recorded using a spectrophotometer 2550 (Shimadzu-UV, Japan).The geometry ofallstudied compounds was optimized by the DFT/B3LYP/Def2-SVP method. The energy of electron levels in the S0 state and the distribution of electron density at each MO were obtained by the DFT/CAMB3LYP/cc-pVDZ method.The energies of excited states were obtained by the TDDFT/CAMB3LYP/cc-pVDZ, ADC(2)/cc-pVDZ and EOM-DLPNO/cc-pVDZmethods.All DFT and TDDFT calculations were carried out in the GAMESS (US)software computing package. ADC(2) calculations of excited states were performed using the Orca 4.0.1software package. EOM-DLPNO and OVGFcalculations were carried out in the Gaussian 16software package.

Complexes of LiF and LiCl with LiF, LiCl, LiH, HF, HCl, H2, Li2, F2, Cl2, FCl, H2O and NH3. Structures, energies and vibrational frequencies

Using coupled cluster calculations with quadruple-zeta basis sets optimal structures and dissociation energies were obtained for complexes of LiF and LiCl with LiH, HF, HCl, H2, Li2, F2, Cl2, FCl, H2O and NH3. Structures for LiF-LiF and LiCl-LiCl have D2h symmetry, while the structure of LiF-LiCl, as well as structures of LiF and LiCl with LiH, HF and Li2 are cyclic, with C2v symmetry. Most other systems have Cs symmetry, many in near-cyclic form. The largest dissociation energy of 21,304 cm−1 was obtained for LiF-LiF. Dissociation energies for LiCl-LiCl and for cyclic C2v systems range from about 10,000 to 20,000 cm−1. For cyclic systems with D2h and C2v symmetries harmonic vibrational frequencies cannot be related to monomer frequencies. Their higher frequencies, however, are close to frequencies of triatomic Li-Y-Li, with Y = H, F, Cl, and to frequencies of F-H-F-.

Electron Spin Resonance of V4+ Ions in K2O-B2O3-V2O5 Glasses

In the present work the ESR study of potassium borovanadate (K2O-B2O3-V2O5) glasses is reported at room temperature and liquid nitrogen temperature. The spectra at liquid nitrogen temperature is similar to at room temperature except the indusial hyperfine lines are sharper and more intense which might be ascribed to a spin-lattice relaxation effect. The ESR parameters were calculated at room temperature and shows that in-plane π bonding is somewhat covalent and covalency is nearly independent of concentration of K2O. The octahedral site with a tetragonal compression gives g value in the order g׀׀&lt; g&lt; ge(=2.0023). It is observed that the V4+ ions in the present sample exist as VO2+ ions in octahedral coordination with a tetragonal compression and belong to C4v symmetry.

In Vitro Studies Demonstrate Antitumor Activity of Vanadium Ions from a CaO-P2O5-CaF2:V2O5 Glass System in Human Cancer Cell Lines A375, A2780, and Caco-2.

In this research, we investigated the structural and biological properties of phosphate glasses (PGs) after the addition of V2O5. A xV2O5∙(100 − x)[CaF2∙3P2O5∙CaO] glass system with 0 ≤ x ≤ 16 mol% was synthesized via a conventional melt-quenching technique. Several analysis techniques (dissolution tests, pH, SEM-EDS, FT-IR, and EPR) were used to obtain new experimental data regarding the structural behavior of the system. In vitro tests were conducted to assess the antitumor character of V2O5-doped glass (x = 16 mol%) compared to the matrix (x = 0 mol%) and control (CTRL-) using several tumoral cell lines (A375, A2780, and Caco-2). The characterization of PGs showed an overall dissolution rate of over 90% for all vitreous samples (M and V1−V7) and the high reactivity of this system. EPR revealed a well-resolved hyperfine structure (hfs) typical of vanadyl ions in a C4v symmetry. FT-IR spectra showed the presence of all structural units expected for P2O5, as well as very clear depolymerization of the vitreous network induced by V2O5. The MTT assay indicated that the viability of tumor cells treated with V7-glass extract was reduced to 50% when the highest concentration was used (10 µg/mL) compared to the matrix treatment (which showed no cytotoxic effect at any concentration). Moreover, the matrix treatment (without V2O5) provided an optimal environment for tumor cell attachment and proliferation. In conclusion, the two types of treatment investigated herein were proven to be very different from a statistical point of view (p < 0.01), and the in vitro studies clearly underline the cytotoxic potential of vanadium ions from phosphate glass (V7) as an antitumor agent.