Type I and Type II Photosensitized Oxidation Reactions: Guidelines and Mechanistic Pathways

Here, 10 guidelines are presented for a standardized definition of type I and type II photosensitized oxidation reactions. Because of varied notions of reactions mediated by photosensitizers, a checklist of recommendations is provided for their definitions. Type I and type II photoreactions are oxygen‐dependent and involve unstable species such as the initial formation of radical cation or neutral radicals from the substrates and/or singlet oxygen (¹O₂ ¹?_g) by energy transfer to molecular oxygen. In addition, superoxide anion radical () can be generated by a charge‐transfer reaction involving O₂ or more likely indirectly as the result of O₂‐mediated oxidation of the radical anion of type I photosensitizers. In subsequent reactions, may add and/or reduce a few highly oxidizing radicals that arise from the deprotonation of the radical cations of key biological targets. can also undergo dismutation into H₂O₂, the precursor of the highly reactive hydroxyl radical () that may induce delayed oxidation reactions in cells. In the second part, several examples of type I and type II photosensitized oxidation reactions are provided to illustrate the complexity and the diversity of the degradation pathways of mostly relevant biomolecules upon one‐electron oxidation and singlet oxygen reactions.     

Photocatalysis of Chloroform Decomposition by Tetrachlorocuprate (II) on Dowex 2‐X8

Heterogenized on a polystyrene anion exchange resin and in the presence of oxygen, catalyzes the photodecomposition of chloroform at wavelengths above 345 nm with greater efficiency than an equivalent amount in homogeneous solution. The reaction is proposed to proceed in two stages, the first stage yielding CCl₄ and as products, the second consisting of a chain reaction resulting from the ‐catalyzed photodissociation of CCl₄, yielding phosgene with CCl₃ radicals as chain carriers. Photodecomposition is retarded by added Cl^?, CH₃CN, C₆H₁₂ or C₂H₅OH, which is ascribed to the displacement of CHCl₃ molecules from the vicinity of the copper by attraction to the polystyrene matrix or to the alkylammonium cation sites.     

A Family of Potent Ru(II) Photosensitizers with Enhanced DNA Intercalation: Bimodal Photokillers

A new family of Ru(II)‐based photosensitizers was synthesized and systematically characterized. The ligands employed to coordinate the ruthenium metal center were the commercially available 2,2′‐bipyridine and a pyridine‐quinoline hybrid bearing an anthracene moiety. The complexes obtained carry either or Cl^? counterions. These counterions determine the complexes' hydrophobic or hydrophilic character, respectively, therefore dictating their solubility in biologically related media. All photosensitizers exhibit characteristic, relatively strong and wide UV–Vis absorption spectral profiles. Their high efficiency in generating cytotoxic singlet oxygen was established (up to Φ_Δ ~0.8). Moreover, the interaction of these photosensitizers with double‐stranded DNA was studied fluoro‐ and photospectroscopically and their binding affinities were found to be of the order of 3 × 10⁷ M^?1. All complexes are photocytotoxic to DU145 human prostate cancer cells. The highest light‐induced toxicity was conferred by the photosensitizers bearing Cl^? counterions, probably due to the looser ionic “chaperoning” of Cl^?, in comparison to , leading to higher cell internalization.     

Hybrid Membrane of Agarose and Lanthanide Coordination Polymer: a Selective and Sensitive Fe3+ Sensor

A new hybrid membrane was prepared by a facile method based on a highly luminescent lanthanide coordination polymer and agarose. The soft membrane was characterized by FT‐IR, PXRD, SEM and luminescence. It is found that the soft membrane is a highly selective and sensitive sensor, among 19 metal ion solutions of Fe³⁺, Mg²⁺, Li⁺, Ca²⁺, Zn²⁺, Cu²⁺, Ba²⁺, Mn²⁺, Ru³⁺, Cr³⁺, Ag⁺, Sr²⁺, Cd²⁺, Na⁺, Ni²⁺, Pb²⁺, Fe²⁺, Hg²⁺ and Ca²⁺, only Fe³⁺ quench the luminescence. The sensing results can be distinguished by the naked eye in daylight or by irradiation of a portable UV light at the scene. Mechanism studies reveal the sensing is due to the decomposition of the coordination polymer 1 which induced by slow permeation of Fe³⁺. Further studies found anions of ${\mathbf{BO}}_{\mathbf{3}}^{?}$, ${\mathbf{CO}}_{\mathbf{3}}^{\mathbf{2}?}$, ${\mathbf{H}}_{\mathbf{2}}{\mathbf{PO}}_{\mathbf{4}}^{?}$, Br^?, Cl^?, ${\mathbf{ClO}}_{\mathbf{4}}^{?}$, ${\mathbf{H}}_{\mathbf{2}}{\mathbf{PO}}_{\mathbf{4}}^{?}$, I^?, ${\mathbf{IO}}_{\mathbf{3}}^{?}$ and ${\mathbf{NO}}_{\mathbf{3}}^{?}$ will not quench the luminescence of the hybrid membrane, which imply that other anions in water would not disturb the detection result.     

The Effects of Supply on Mazzaella laminarioides (Rhodophyta,Gigartinales) from Southern Chile

The effects of nitrate supply on growth, pigments, mycosporine‐like amino acids (MAAs), C:N ratios and carrageenan yield were investigated in Mazzaella laminarioides cultivated under solar radiation. This species is economically important in southern Chile where an increase of nitrogen in coastal waters is expected as a consequence of salmon aquaculture activity. Apical segments were cultivated in enriched seawater with five different concentrations (0, 0.09, 0.18, 0.38 and 0.75 mm ) during 18 days. Although phycoerythrin and phycocyanin content, as well as C:N ratios, were reduced in the control treatment (without supply), when compared to treatments, total MAA concentration, carrageenan yield and growth rates were similar in all tested conditions. Nevertheless, during the experiment, an important synthesis of mycosporine‐glycine took place in a nitrate concentration‐dependent manner, with accumulation being saturated around 0.18 mm of nitrate. These results indicate that exposure to high concentration of more than 100 times the values observed in the nature did not impair the photoprotection system, as determined by MAAs, nor did it have a deleterious effect on growth or carrageenan yield of M. laminarioides, a late successional species from Chile.     

Chemiluminescence of Cigarette Smoke: Salient Features of the Phenomenon

The study disclosed herein provides for the first time a detailed experimental support for the general mechanism of the cigarette‐smoke‐derived chemiluminescence, as an example par excellence of the excited‐state generation in a chemically complex aerosol medium. The mechanism involves chemiexcitation in a unimolecular transformation of the smoke‐borne free radical species. However, the concentration of these radicals, , obeys a bimolecular (second‐order) kinetics and depends on a particulate‐phase content (total particulate matter, TPM) of the cigarette smoke. The decrease in with increasing the TPM amount manifests radical‐scavenging propensity of the smoke particulate phase. Astonishingly, no energy transfer takes place from the primary excited light‐emitting species to luminophoric molecules abundant in the smoke. The reported results build up fundamentals of a facile chemiluminescence assay for free radical properties of the smoke. The experimental approaches developed for this study are of general scope and may be used for mechanistic elucidation of the excited‐state generation in chemical systems and environments of an arbitrary complexity.     

Photophysical Properties of Fluorescent 2‐(Phenylamino)‐1,10‐phenanthroline Derivatives†

The present study details the experimental and theoretical characterization of the photophysical properties of 14 examples of 2‐(phenylamino)‐1,10‐phenanthrolines ( 1 ). The absorption spectra of 1 are substituent‐dependent but in a general manner present absorption bands at wavelengths of ~230; ~300; ~335 and a shoulder at ~380 nm. Electron‐donating groups (EDG) and electron‐withdrawing groups (EWG), respectively, result in bathochromic and hypsochromic shifts. Compounds 1 are highly luminescent, in contrast to phenanthroline, and emit in the region between 350 and 500 nm with substituent‐dependent λ_max emission. The emission spectra show a redshift for EDG (4‐OMe 62 nm; 4‐Me 19 nm) and a blueshift for EWG (4‐CN 41 nm; 4‐CF₃ 38 nm) relative to the emission of the unsubstituted parent compound 1a . Plotting the ${\mathbf{\lambda }}_{\mathbf{max}}^{\mathbf{\text{EM}}}$ against Hammett σ+ constants gave an excellent linear correlation demonstrating the electron‐deficient nature of the excited state and how the substituents (de)stabilize S₁. Theoretical calculations revealed a HOMO‐LUMO π‐π* electronic transition to S₁ which in combination with difference (S₁–S₀) in electron density maps revealed charge‐transfer character. Strongly electron‐withdrawing substituents switch off the charge transfer to give rise to a local excitation.     

Synthesis,Characterization and Photocatalytic Activity of Ag+‐ and Sn2+‐Doped KTi0.5Te1.5O6

In this study, the photocatalytic dye degradation efficiency of KTi_0.5Te_1.5O₆ synthesized through solid‐state method was enhanced by cation (Ag⁺/Sn⁺²) doping at potassium site via ion exchange method. As prepared materials were characterized by XRD, SEM‐EDS, IR, TGA and UV–Vis Diffuse reflectance spectroscopic (DRS) techniques. All the compounds were crystallized in cubic lattice with space group. The bandgap energies of parent, Ag⁺‐ and Sn⁺²‐doped KTi_0.5Te_1.5O₆ materials obtained from DRS profiles were found to be 2.96, 2.55 and 2.40 eV, respectively. Photocatalytic efficiency of parent, Ag⁺‐ and Sn⁺²‐doped materials was evaluated against the degradation of methylene blue (MB) and methyl violet (MV) dyes under visible light irradiation. The Sn⁺²‐doped KTi_0.5Te_1.5O₆ showed higher activity toward the degradation of both MB and MV dyes and its higher activity is ascribed to the lower bandgap energy compared to the parent and Ag⁺‐doped KTi_0.5Te_1.5O₆. The mechanistic degradation pathway of methylene blue (MB) was studied in the presence of Sn²⁺‐doped KTi_0.5Te_1.5O₆. Quenching experiments were performed to know the participation of holes, super oxide and hydroxyl radicals in the dye degradation process. The stability and reusability of the catalysts were studied.     

Generation of 8‐oxo‐7,8‐dihydroguanine in G‐Quadruplexes Models of Human Telomere Sequences by One‐electron Oxidation

The mechanistic aspects of one‐electron oxidation of G‐quadruplexes in the basket (Na⁺ ions) and hybrid (K⁺ ions) conformations were investigated by transient absorption laser kinetic spectroscopy and HPLC detection of the 8‐oxo‐7,8‐dihydroguanine (8‐oxoG) oxidation product. The photo‐induced one‐electron abstraction from G‐quadruplexes was initiated by sulfate radical anions (SO₄˙^?) derived from the photolysis of persulfate ions by 308 nm excimer laser pulses. In neutral aqueous solutions (pH 7.0), the transient absorbance of neutral guanine radicals, G(‐H)˙, is observed following the complete decay of SO₄˙^? radicals (~10 μs after the actinic laser flash). In both basket and hybrid conformations, the G(‐H)˙ decay is biphasic with one component decaying with a lifetime of ~0.1 ms, and the other with a lifetime of 20–30 ms. The fast decay component (~0.1 ms) in G‐quadruplexes is correlated with the formation of 8‐oxoG lesions. We propose that in G‐quadruplexes, G(‐H)˙ radicals retain radical cation character by sharing the N1‐proton with the O⁶‐atom of G in the [G˙⁺: G] Hoogsteen base pair; this [G(‐H)˙: H⁺G G˙⁺: G] leads to the hydration of G˙⁺ radical cation within the millisecond time domain, and is followed by the formation of the 8‐oxoG lesions.     

Photo‐Fenton and Riboflavin‐photosensitized Processes of the Isoxaflutole Herbicide

The proherbicide Isoxaflutole (IXF) hydrolyzes spontaneously to diketonitrile (DKN) a phytotoxic compound with herbicidal activity. In this work, the sensitized degradation of IXF using Riboflavin (Rf), a typical environmentally friendly sensitizer, Fenton and photo‐Fenton processes has been studied. The results indicate that only the photo‐Fenton process produces a significant degradation of the IXF. Photolysis experiments of IXF sensitized by Riboflavin is not a meaningful process, IXF quenches the Rf excited triplet (³Rf*) state with a quenching rate constant of 1.5 · 10⁷ m ^?1 s^?1 and no reaction is observed with the species O₂(¹Δ_g) or ${\mathrm{O}}_2^{·?}$ generated from ³Rf*. The Fenton reaction produces no changes in the IXF concentration. While the photo‐Fenton process of the IXF, under typical conditions, it produces a degradation of 99% and a mineralization to CO₂ and H₂O of 88%. A rate constant value of 1.0 × 10⁹ m ^?1 s^?1 was determined for the reaction between IXF and HO˙. The photo‐Fenton process degradation products were identified by UHPLC‐MS/MS analysis.     

Effects of Ultraviolet Radiation (UV‐A+UV‐B) on the Antioxidant Metabolism of the Red Macroalga Species Acanthophora spicifera (Rhodophyta,Ceramiales) From Different Salinity and Nutrient Conditions

Acanthophora spicifera (M.Vahl) Børgesen is a macroalga of great economic importance. This study evaluated the antioxidant responses of two algal populations of A. spicifera adapted to different abiotic conditions when exposed to ultraviolet‐A+ultraviolet‐B radiation (UV‐A+UV‐B). Experiments were performed using the water at two collection points for 7 days of acclimatization and 7 days of exposure to UVR (3 h per day), followed by metabolic analyses. At point 1, water of 30 ± 1 practical salinity unit (psu) had concentrations of 1.06 ± 0.27 mm ${\text{NH}}_4^{+}$, 8.47 ± 0.01 mm ${\text{NO}}_3^{?}$, 0.17 ± 0.01 mm ${\text{PO}}_4^{?3}$ and pH 7.88. At point 2, water of 35 ± 1 psu had concentrations of 1.13 ± 0.05 mm ${\text{NH}}_4^{+}$, 3.73 ± 0.01 mm ${\text{NO}}_3^{?}$, 0.52 ± 0.01 mm ${\text{PO}}_4^{?3}$ and pH 8.55. Chlorophyll a, phycobiliproteins, carotenoids, mycosporins, polyphenolics and antioxidant enzymes (catalase, superoxide dismutase and guaiacol peroxidase) were evaluated. The present study demonstrates that ultraviolet radiation triggers antioxidant activity in the A. spicifera. However, such activation resulted in greater responses in samples of the point 1, with lower salinity and highest concentration of nutrients.     

Photodynamic Action Mechanism Mediated by Zinc(II) 2,9,16,23‐Tetrakis[4‐(N‐methylpyridyloxy)]phthalocyanine in Candida albicans Cells

The photoreaction type I/type II pathways mediated by zinc(II) 2,9,16,23‐tetrakis[4‐(N‐methylpyridyloxy)]phthalocyanine (ZnPPc⁴⁺) was studied in Candida albicans cells. This photosensitizer was strongly bound to C. albicans cells at short times. After 30 min irradiation, 5 μM ZnPPc⁴⁺ produced ~5 log decrease in cell viability. Different probes were used to detect reactive oxygen species (ROS) in cell suspensions (~10⁶ CFU mL^?1). Singlet molecular oxygen, O₂(¹Δ_g), was observed by the reaction with 9,10‐dimethylanthracene (DMA) and tetrasodium 2,2‐(anthracene‐9,10‐diyl)bis(methylmalonate) (ABMM), whereas the nitro blue tetrazolium (NBT) method was used to sense superoxide anion radical (). Moreover, the effects produced by an anoxic atmosphere and cell suspensions in D₂O, as well as the addition of sodium azide and mannitol as ROS trapping were evaluated in the PDI of C. albicans. These investigation indicates that O₂(¹Δ_g) is generated in the cells, although a minor extension other radical species can also be involved in the PDI of C. albicans mediated by ZnPPc⁴⁺.     

The Effect of Endothelial Cells on UVB‐induced DNA Damage and Transformation of Keratinocytes In 3D Polycaprolactone Scaffold Co‐culture System

Nitric oxide ( ${\mathbf{NO}}^{·}$) plays an important role in the regulation of redox balance in keratinocytes post‐UVB exposure. Since endothelial cells releases ${\mathbf{NO}}^{·}$ for a prolonged time post‐UVB, we determined whether human umbilical vein endothelial cells (HUVEC) could have an effect on UVB‐induced DNA damage and transformation of their adjacent keratinocytes (HaCaT) using a 3D cell co‐culturing system. Our data show that the levels of DNA breaks and/or cyclobutane pyrimidine dimer (CPD) along with γH2AX are higher in the co‐cultured than in the mono‐cultured keratinocytes post‐UVB. The ${\mathbf{NO}}^{·}$ level in the co‐cultured cells is increased approximately 3‐fold more than in mono‐cultured HaCaT cells within 1‐hour post‐UVB but then is reduced quickly in co‐cultured HaCaT cells comparing to mono‐cultured cells from 6 to 24 h post‐UVB. However, the peroxynitrite (ONOO^?) level is higher in the co‐cultured than in the mono‐cultured HaCaT cells in whole period post‐UVB. Furthermore, while expression level of inducible nitric oxide synthase (iNOS) is increased, the ratio of coupled/uncoupled eNOS is reduced in co‐cultured HaCaT cells compared to mono‐cultured HaCaT cells. Finally, the co‐cultured cells have a significantly increased transformation efficiency after repeating UVB exposure compared to mono‐culture HaCaT cells. Our results suggest that endothelial cells could enhance ${\mathbf{NO}}^{·}$/ONOO^? imbalance and promote transformation of adjacent keratinocytes.     

Addition of Hydrogen Peroxide to Groundwater with Natural Iron Induces Water Disinfection by Photo‐Fenton at Circumneutral pH and other Photochemical Events

Samples of natural groundwater (with low turbidity, neutral pH and 0.3 mg L^?1 iron concentration) inoculated with Escherichia coli K‐12 were exposed to simulated solar light both in the presence and in the absence 10 mg L^?1 of H₂O_2. Results demonstrated that the viability of E. coli (by DVC–FISH) was grounded to zero after 360 min of irradiation. This abatement could be caused by the oxidative stress induced by radicals or another photo‐induced reactive oxygen species. Two 2³ factorial experimental designs enabled the evaluation of the effects of chemical factors on the inactivation of E. coli. The first experimental design considered the pH, iron and H₂O₂, while the second evaluated the ions fluoride, carbonate and phosphate found in groundwater. pH was found to play a key role in the inactivation of E. coli. The best reduction in viability was obtained at the lower pH (6.75), while a nonsignificant effect was observed when iron or H₂O₂ concentrations were raised. At higher concentrations, anions, such as carbonate and phosphate, negatively affected the E. coli abatement. However, a higher concentration of fluoride accelerated it. In all experiments, the pH was observed to rise to values higher than 8.0 units after 360 min of treatment.     

The Trifluoromethyl Anion: Evidence for [K(crypt‐222)]+

[K(crypt‐222)]⁺ ( 1 ) and [K(crypt‐222)]⁺ ( 3 ) are isostructural, displaying nearly identical unit cell parameters. The two structures are similar to the extent that the previously reported [K(crypt‐222)]⁺ model can be refined against the new data for [K(crypt‐222)]⁺ , with extra electron density being observed from the fourth fluorine atom of the . In agreement with experimental observations, theoretical calculations suggest that deprotonated [K(crypt‐222)]⁺ is highly unstable even at as low as 195 K. The previously considered 1:1 CHF ₃ clathrate of deprotonated [K(crypt‐222)]⁺ (crystallographically indistinguishable from 1 ) is ruled out on the basis of all available data.     

Physicochemical and Electronic Properties of Cationic [6]Helicenes: from Chemical and Electrochemical Stabilities to Far‐Red (Polarized) Luminescence

The physicochemical properties of cationic dioxa ( 1 ), azaoxa ( 2 ), and diaza ( 3 ) [6]helicenes demonstrate a much higher chemical stability of the diaza adduct 3 (pK_R+=20.4, =?0.72 V) compared to its azaoxa 2 (pK_R+=15.2, =?0.45 V) and dioxa 1 (pK_R+=8.8, =?0.12 V) analogues. The fluorescence of these cationic chromophores is established, and ranges from the orange to the far‐red regions. From 1 to 3 , a bathochromic shift of the lowest energy transitions (up to 614 nm in acetonitrile) and an enhancement of the fluorescence quantum yields and lifetimes (up to 31 % and 9.8 ns, respectively, at 658 nm) are observed. The triplet quantum yields and circularly polarized luminescence are also reported. Finally, fine tuning of the optical properties of the diaza [6]helicene core is achieved through selective and orthogonal post‐functionalization reactions (12 examples, compounds 4 – 15 ). The electronic absorption is modulated from the orange to the far‐red spectral range (560–731 nm), and fluorescence is observed from 591 to 755 nm with enhanced quantum efficiency up to 70 % (619 nm). The influence of the peripheral auxochrome substituents is rationalized by first‐principles calculations.     

An Experimental Study of the Kinetics of the Reactions of Isopropyl,sec‐Butyl,and tert‐Butyl Radicals with Molecular Chlorine at Low Pressures (0.5–7.0 Torr) in the Temperature Range 190–480 K

In this work, we have measured the rate coefficients of the reactions of isopropyl (propan‐2‐yl), sec‐butyl (butan‐2‐yl), and tert‐butyl (2‐methylpropan‐2‐yl) radicals with molecular chlorine as a function of temperature (190–480 K). The experiments were done in a tubular laminar flow reactor coupled to a photoionization quadrupole mass spectrometer employing a gas‐discharge lamp for ionization. The radicals were homogeneously produced in the reactor by photolyzing suitable precursor molecules with 193‐nm pulsed exciplex laser radiation. The bimolecular rate coefficients were obtained by monitoring the radical decay signals in real time under pseudo–first‐order conditions. The rate coefficients of all three reactions showed negative temperature dependence. The bath gas used in the experiments was helium, and the rate coefficients appeared to be independent of the helium concentrations employed ([2.4–14] × 10¹⁶ cm^?3) for all three reactions. The rate coefficients of the reactions can be approximated in the studied temperature range by the following parameterizations: We estimate that the overall uncertainties of the measured rate coefficients are ±20%. We were able to observe 2‐chloropropane (i‐C₃H₇Cl) product for the i‐C₃H₇^● + Cl₂ reaction. No products were observed for the other two reactions, and the reasons for this are briefly discussed in the text.     

Correlating Boron–Hydrogen Stretching Frequencies with Boron–Hydrogen Bond Lengths in Closoboranes: An Approach Using DFT Calculations

Using harmonic and anharmonic DFT calculations, we have established a general correlation between B–H stretching frequencies and B–H bond lengths valid for the closoboranes (x = 6 – 12), substituted closoboranes B₁₂H_{12 –} (with X = F, Cl, Br and n = 1 – 3 and 9 – 12) and the carboranes and , suggesting that this correlation is also applicable to other similar species. It appears that the average B–H stretching frequency observed around 2500 cm⁻¹ shift by about −100 cm⁻¹ if the average B–H bond length increases by 1 pm. In contrast to , the B–H bond in closoboranes is practically covalent and the correlation evidenced between its stretching frequency and its length proves to be similar to the one observed for the C–H bond.     

Carbon–sulfur chains: A high‐resolution infrared and quantum‐chemical study of C3S and SC7S

In the course of a 5 μm high‐resolution infrared study of laser ablation products from carbon–sulfur targets, the ν₁ vibrational mode region of linear C₃S has been studied continuously from 2046 to 2065 cm^?1. Besides the prominent vibrational fundamental, the region was found to feature the , and even hot bands, the latter two of which were observed for the first time. Owing to the high signal‐to‐noise ratio obtained, the ν₁ mode of S could also be observed in natural abundance for the first time at high spectral resolution in the infrared. At 2061 cm^?1, hidden inside the branch of the C₃S ν₁ fundamental mode, a weak new band is observed which exhibits very tight line spacing and stems from a heavy both carbon and sulfur containing carrier. On the basis of high‐level quantum‐chemical calculations of selected carbon–sulfur chains and other carbon‐rich cumulenes, this feature is attributed to the ν₅ vibrational fundamental of linear SC₇S, which stands for the first gas‐phase spectroscopic detection of this long cumulenic chain.     

Theoretical prediction of the optical rotation of chiral molecules in ordered media: A computational study of (Ra)‐1,3‐dimethylallene, (2R)‐2‐methyloxirane,and (2R)‐N‐methyloxaziridine

A theoretical procedure has been developed and implemented to calculate the optical rotation of chiral molecules in ordered phase via origin‐independent diagonal components , of the optical activity tensor and origin‐independent components , for , of the mixed electric dipole‐electric quadrupole polarizability. Origin independence was achieved by referring these tensors to the principal axis system of the electric dipole dynamic polarizability at the same laser frequency ω. The approach has been applied, allowing for alternative quantum mechanical methods based on different gauges, to estimate near Hartree–Fock values for three chiral molecules, (2R)‐N‐methyloxaziridine C₂NOH₅, (2R)‐2‐methyloxirane (also referred to as propylene oxide) C₃OH₆, and ( )‐1,3‐dimethylallene C₅H₈, at two frequencies. The theoretical predictions can be useful for an attempt at measuring correspondent experimental values in crystal phase. © 2015 Wiley Periodicals, Inc.