Iodine Atoms Research Articles

REGULARITIES OF PHYSICO-CHEMICAL INTERACTION IN THE QUASIBINARY SYSTEMS BASED ON THE TERNARY HALIDES Rb3(Cs3)Sb2(Bi2)Br9(I9) AND K2(Rb2,Cs2,Tl2)TeBr6(I6): EXPLANATION WITHIN THE FRAMEWORK OF THE BOND VALENCE MODEL

The work is the first attempt to employ the bond valence model (BVM) in the explanation and interpretation of the phase diagrams observed for the quasibinary systems based on the ternary halides Rb3(Cs3)Sb2(Bi2)Br9(I9) (A3B2X9) and K2(Rb2,Cs2,Tl2)TeBr6(I6) (A2BX6) belonging to the structural family of perovskite. The most characteristic features of the phase diagrams of such systems are (a) a monotonic increase in the melting and crystallization temperatures when the smaller A atom is replaced by a larger chemical analogue; (b) a gradual decrease in the melting and crystallization temperatures when the bromine atoms are replaced by iodine atoms, reaching the temperature minimum at a molar ratio of ~1 : 1, and then an increase of the temperatures to the pure iodine component of the system. With the isostructurality of the starting components, in case (a) a continuous series of solid solutions (CSSS) of substitution is formed, without a temperature minimum; if the starting components belong to different structural types, then a peritectic interaction with the wide concentration limits of solid solutions is observed. Under the same conditions concerning the isostructurality/non-isostructurality of starting components, in case (b), correspondingly, either a CSSS of substitution with a temperature minimum is formed or eutectic interaction with the wide concentration limits of solid solutions is observed.
 Within the framework of the BVM, in case (a) a monotonic increase of the melting and crystallization temperatures when replacing a smaller atom A with a larger analogue can be interpreted as a consequence of reducing the deficit of the bond valence sum (BVS) for cations A, resulting in the stabilization of the structure as a whole. In case (b), partial replacement of one halogen ion by a halogen ions of another sort leads either to a deficit (if a larger anion is replaced by a smaller one) or to an excess (if a smaller anion is replaced by a larger one) of the BVS values for the cations A and for the anion that replaced the main halogen sort. An increase in the excess or deficit of the BVS values destabilizes the structure of ternary halides, reducing the melting and crystallization temperatures; the maximum destabilization is achieved at a ~1 : 1 molar ratio of the components, which is expressed in reaching the characteristic temperature minimum of the respective systems.
 The approach described in the work can expectedly be employed in explanation and interpretation of another phase diagrams based on the structures featuring the closest packing formed by alkaline metals and halogens.
 Keywords: ternary halides; crystal structures; phase diagrams; bond valence model.

2,5-Diiodothiophene: A Versatile Halogen Bonding Synthon for Crystal Engineering

Relative to the common diiodobenzene-based halogen bond donors, little is known about the halogen bonding of iodine-substituted thiophene compounds. A series of co-crystallization experiments were performed using the sulfur-atom-containing halogen bond donor 2,5-diiodothiophene with N-heterocyclic diamines, as well as ammonium iodide salts. These results reveal a wide range of halogen bonding motifs tied to the halogen bond donor/acceptor stoichiometry. While, in acceptor-rich stoichiometries, discrete units prevail through C–I···I halogen bonds, donor-rich stoichiometries encourage the formation of two-dimensional halogen bonding networks, often with the additional involvement C–I···S and S···S interactions. Halogen bonding through the C–I iodine atom predominates in all structures. The measured halogen bond distances fall between those typically observed for 1,4-diiodobenzene and 1,4-diiodotetrafluorobenzene, reaffirming the role of fluorination in strengthening the halogen bond while also expanding the library of halogen bonding synthons to donors having intermediate electrostatic potentials.

Microscopic origin of multiferroic order in monolayer NiI2

The discovery of multiferroic behavior in monolayer NiI2 provides a new symmetry-broken state in van der Waals monolayers, featuring the simultaneous emergence of helimagnetic order and ferroelectric order at a critical temperature of T = 21 K. However, the microscopic origin of multiferroic order in NiI2 monolayer has not been established, and in particular, the role of non-collinear magnetism and spin–orbit coupling in this compound remains an open problem. Here we reveal the origin of the two-dimensional multiferroicity in NiI2 using first-principles electronic structure methods. We show that the helimagnetic state appears as a consequence of the long-range magnetic exchange interactions, featuring sizable magnetic moments in the iodine atoms. We demonstrate that the electronic density reconstruction accounting for the ferroelectric order emerges from the interplay of non-collinear magnetism and spin–orbit coupling. We demonstrate that the ferroelectric order is controlled by the iodine spin–orbit coupling, and leads to an associated electronically-driven distortion in the lattice. Our results establish the microscopic origin of the multiferroic behavior in monolayer NiI2, putting forward the coexistence of helical magnetic order and ligand spin–orbit coupling as driving forces for multiferroic behavior in two-dimensional materials.

Visualizing Chemical Reactions with X-rays

The recombination of laser-dissociated iodine molecules dissolved in CCl4 is explored by time-resolved x-ray diffraction. The x-raypulses employed in our experiments were generated by the ESRF synchrotron in Grenoble. The solvent contribution to the measured signals was eliminated using appropriate experimental procedures. Motions of iodine atoms were then studied from 200 ps to 10 ps. Different relaxation processes are shown to operate in this time domain. It is proved that the iodine recombination follows two reaction paths, taking place in the electronic states X and A/A' of I2, respectively. In spite of widely different experimental approaches, laser optical and x-ray studies provide a similar picture of this prototype reaction.

Iodine-doped fibrous sulfurized polyacrylonitrile with accelerated reaction kinetics

Sulfurized polyacrylonitrile (SPAN) is a promising candidate cathode material for the next-generation lithium-metal batteries due to its unique chemical structure and excellent electrochemical stability. Although SPAN is a type of conductive conjugated polymer, it suffers from the slow reaction kinetics resulting from its insufficient electronic conductivity. In this work, we propose a freestanding fibrous SPAN with an accelerated reaction kinetics by iodine doping. According to Raman, X-ray photoelectron spectroscopy and thermal analysis, sulfur and iodine atoms existing in the form of C–S/S–S and C–I bonds in the iodine-doped sulfurized polyacrylonitrile (I-SPAN), respectively. The electrochemical tests reveal that the charge transfer in I-SPAN improved significantly. A high reversible specific capacity of 1201 mAh g−1 is achieved after 400 cycles at 1000 mA g−1.

Determining the charge distribution and the direction of bond cleavage with femtosecond anisotropic x-ray liquidography

Energy, structure, and charge are fundamental quantities characterizing a molecule. Whereas the energy flow and structure change in chemical reactions are experimentally characterized, determining the atomic charges of a molecule in solution has been elusive, even for a triatomic molecule such as triiodide ion, I3−. Moreover, it remains to be answered how the charge distribution is coupled to the molecular geometry; which I-I bond, if two I-I bonds are unequal, dissociates depending on the electronic state. Here, femtosecond anisotropic x-ray solution scattering allows us to provide the following answers in addition to the overall rich structural dynamics. The analysis unravels that the negative charge of I3− is highly localized on the terminal iodine atom forming the longer bond with the central iodine atom, and the shorter I-I bond dissociates in the excited state, whereas the longer one in the ground state. We anticipate that this work may open a new avenue for studying the atomic charge distribution of molecules in solution and taking advantage of orientational information in anisotropic scattering data for solution-phase structural dynamics.

Differentiation Between Solitary Pulmonary Inflammatory Lesions and Solitary Cancer Using Gemstone Spectral Imaging.

The distinction between solitary inflammatory lesion and solitary lung cancer remains a challenge because of their considerable overlapping computed tomography (CT) imaging features. This study aimed to verify whether spectral CT parameters can differentiate solitary lung cancer from solitary inflammatory lesions and to find their correlations with lesion size. A total of 78 patients with solitary lung lesions were included in our study. All of them underwent enhanced CT scans with Gemstone Spectral Imaging (GSI) mode, which was one of the dual-energy imaging technologies. According to maximum diameter (Dmax) of the lesion, regions of interest were collected and divided into inflammatory (group I: <3 cm [IA], n = 17; ≥3 cm [IB], n = 14) and cancer groups (group II: <3 cm [IIA], n = 20; ≥3 cm [IIB], n = 27). Computed tomography values (HU40keV, HU70keV), effective atomic number (Zeff), iodine concentration (IC), normalized IC (NIC), and spectral curve slopes (λ30, λ40) of each region of interest were calculated. The NIC was defined as the IC ratio of the lesion to the descending aorta. Mann-Whitney U test was used for intergroup (I vs II, IA vs IIA, IB vs IIB) and intragroup (IA vs IB, IIA vs IIB) comparisons, and receiver operating characteristic curve analysis was performed. Correlation analysis was applied to find the relationship between Dmax and GSI parameters. No significant correlation was found between GSI parameters and Dmax in the inflammatory group, whereas inverse correlations were found in the cancer group. Gemstone spectral imaging parameters (except HU70keV) of group IIA were significantly higher than those of group IIB. There were significant differences in HU40keV, IC, NIC, λ30, and λ40 between groups IB and IIB under both arterial and venous phase (P values < 0.05), whereas the area under the curve for λ30 under venous phase was largest, and sensitivity and specificity were 96.32% and 85.71%, respectively. However, only HU40keV and HU70keV values under the arterial phase of IIA were significantly higher than those of IA. Quantitative parameters of GSI demonstrated an inverse correlation with the lesion size of solitary lung cancer, and GSI parameters can be new ways to differentiate solitary lung cancer from solitary inflammatory lesions.

Element-dependent unique properties of Janus Cr2I3X3 (X = F, Cl, Br) monolayer: Insight from first-principles calculations

Two-dimensional (2D) intrinsic ferromagnetic (FM) semiconductors are important to develop low-dimensional spintronic devices. The recent discovery of FM CrI3 monolayer provides ample opportunities for the spintronic applications of atomically thin magnets. Breaking the structural inversion symmetry of CrI3 would result in some extraordinary physical characteristics. Through first-principles calculations, here we systematically studied the structural, electronic, magnetic and mechanical properties of 2D Janus Cr2I3X3 (X = F, Cl, Br) monolayers, and compared them with those of the pure CrX3 monolayers. The results show that the properties of the Janus Cr2I3X3 (X = F, Cl, Br) monolayers are not within the range between CrI3 and CrX3, but go beyond this range. With the decrease of the atomic number of X elements, from Br to F, the properties of Cr2I3X3 increasingly deviate from that of CrI3 or CrX3. All the element-dependent properties of Cr2I3X3 are closely related with the charge redistribution and structural distortion, which is originated from the substitution of Iodine atoms with X atoms (atomic layer substitution) in the Janus structures. Our study enriches the diversity of Janus 2D materials, and provides the theoretical guidance for the application in spintronic devices.

Synthesis and Characterization of Novel Radiopaque Polycarbonate.

Polymeric materials implanted in the human body are usually invisible under X-ray, and the mixing of heavy metal salts into polymeric materials by physical compounding often poses compatibility problems. A new iodine-containing cyclic carbonate monomer, 4-iodo-N-(2-oxo-1,3-dioxan-5-yl)benzamide (IBTMC), is synthesized, which has a degradable carbonate group as its basic structural unit and iodine atoms attached to the side chain in the form of covalent bonds. The ring-opening polymerization of IBTMC is achieved at room temperature under the catalysis of the solid superbase 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD). The structure and X-ray developing ability of the synthesized polycarbonate are characterized by 1 H-NMR, X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDS), Gel Permeation Chromatography (GPC), and micro-computed tomography (Micro-CT). The iodine atoms remain bound to the polymer as covalent bonds after a series of reactions and exhibit a high level of X-ray opacity. In vitro degradation experiments of the polymer prove that the polymer is degradable.

Effect of the iodine atom position on the phosphorescence of BODIPY derivatives: a combined computational and experimental study.

A new BODIPY derivative (o-I-BDP) containing an iodine atom in the ortho position of the meso-linked phenyl group was prepared. Photophysical and electrochemical properties of the molecule were compared to previously reported iodo BODIPY derivatives, as well as to the non-iodinated analog. While in the case of derivatives featuring iodine substituents in the BODIPY core, efficient population of the triplet state is accompanied by a substantial positive shift of the reduction potential compared to pristine BODIPY, o-I-BDP displays phosphorescence and simultaneously maintains the electrochemical properties of unsubstituted BODIPYs. A theoretical investigation was settled to analyze results and rationalize the influence of iodine position on electronic and photophysical properties, with the purpose of preparing a fully organic phosphorescent BODIPY derivative. TD-DFT and spin-orbit coupling calculations shed light on the subtle effects played by the introduction of iodine atom in different positions of BODIPY.

Cover Feature: Rhodium–Iodide Complex on a Catalytically Active SiO2 Surface for One‐Pot Hydrosilylation–CO2 Cycloaddition (Chem. Eur. J. 5/2022)

Surface Rh species with three iodine atoms showed a high catalytic activity for the hydrosilylation of terminal olefins. The picture indicates three iodides with an ammonium cation “tent” coordinate to Rh, and the hydrosilylation reaction occurs at the electron-rich Rh site. Next, the intermediate reacts with CO2 coming from the factory with the assistance of an iodide, then the final product silyl carbonate is formed. More information can be found in the Research Article by K. Motokura et al. (DOI: 10.1002/chem.202104001).

Site-selective iodine atom transfer in fluorinated alkyl iodides via 1,5-hydrogen atom transfer

The direct and selective functionalization of inert C-H bonds via intramolecular hydrogen atom transfer (HAT) is an increasingly powerful tool in organic synthesis. Herein, we designed an efficient and facile iodine atom transfer in fluorinated alkyl iodides via 1,5-HAT. Our process enables site-selective iodination of unreactive C(sp3)-H bonds to afford di- and tri-fluorinated alkyl iodides in good yields. Furthermore, our process shows excellent atom economy and high functional group tolerance, including methyl, methoxy, chloro, cyano, and silyl moieties.

Zwitterionic iodonium species afford halogen bond-based porous organic frameworks.

Porous architectures characterized by parallel channels arranged in honeycomb or rectangular patterns are identified in two polymorphic crystals of a zwitterionic 4-(aryliodonio)-benzenesulfonate. The channels are filled with disordered water molecules which can be reversibly removed on heating. Consistent with the remarkable strength and directionality of the halogen bonds (XBs) driving the crystal packing formation, the porous structure is stable and fully preserved on almost quantitative removal and readsorption of water. The porous systems described here are the first reported cases of one-component 3D organic frameworks whose assembly is driven by XB only (XOFs). These systems are a proof of concept for the ability of zwitterionic aryliodonium tectons in affording robust one-component 3D XOFs. The high directionality and strength of the XBs formed by these zwitterions and the geometrical constraints resulting from the tendency of their hypervalent iodine atoms to act as bidentate XB donors might be key factors in determining this ability.

Promoting effect of water on light and phenanthroline-diphosphine Cu(I) complex-initiated iodine atom transfer cyclisation.

Water can greatly facilitate the iodine atom transfer cyclisation of 2-allyloxy(or prop-2-yn-1-yloxy)-3-iodo tetrahydropyrans and tetrahydrofurans initiated by phenanthroline-diphosphine Cu(I) complexes under 455 nm light irradiation. Good yields were obtained in a mixture of acetonitrile and water (1 : 4, v/v) or in pure water, whereas no reaction took place in acetonitrile under the otherwise same conditions. The copper complexes are virtually heterogeneous in the water-dominant reaction media, which is believed to be a main reason for the beneficial effect of water.

Effects of the halogenido ligands on the Kumada-coupling catalytic activity of [Ni{ t BuN(PPh2)2-κ2P}X2], X = Cl, Br, I, complexes.

Novel nickel(ii) complexes bearing (tbutyl)bis(diphenylphosphanyl)amine and different halogenido ligands, [Ni(P,P)X2] = [Ni{tBuN(PPh2)2-κ2P}X2], (X = Cl, Br, I) are prepared, characterized by IR and NMR spectroscopy, mass spectrometry and X-ray crystallography, and tested as catalysts in the Kumada cross-coupling reaction of model substituted iodobenzenes and p-tolylmagnesium bromide. The data obtained together with DFT calculations indicate that these new catalysts operate in the Ni(i)–Ni(iii) mode. The highest catalytic activity and selectivity are exhibited by [Ni(P,P)Cl2], which is most easily reduced by the used Grignard reagent to the Ni(i) state. This process is much more energy demanding in the case of the bromido and iodido complexes, causing the appearance of the induction period. [Ni(P,P)Cl2] is also very active in the cross-couplings of substrates with iodine atoms sterically shielded by ortho substituents. The data obtained are in good accordance with the described positive effect of the increased electron-releasing power of N-substituents R′ on the overall catalytic performance of [Ni{R′N(PPh2)2-κ2P}X2] complexes.

Unlocking the Potential of Ru(II) Dual-action Compounds with the Power of the Heavy-atom Effect.

We report the synthesis, photochemical and biological characterization of two new Ru(II) photoactivated complexesbased on [Ru(tpy)(Me2 bpy)(L)]2+ (tpy = 2,2':6',2''-terpyridine, Me2 bpy = 6,6'-dimethyl-2,2'-bipyridine), where L = pyridyl-BODIPY (pyBOD). Two pyBOD ligands were prepared bearing flanking hydrogen or iodine atoms. Ru(II)-bound BODIPY dyes show a red-shift of absorption maxima relative to the free dyes and undergo photodissociation of BODIPY ligands with green light irradiation. Addition of iodine into the BODIPY ligand facilitates intersystem crossing, which leads to efficient singlet oxygen production in the free dye, but also enhances quantum yield of release of the BODIPY ligand from Ru(II). This represents the first report of a strategy to enhance photodissociation quantum yields through the heavy-atom effect in Ru(II) complexes. Furthermore, Ru(II)-bound BODIPY dyes display fluorescence turn-on once released, with a lead analog showing nanomolar EC50 values against triple negative breast cancer cells, >100-fold phototherapeutic indexes under green light irradiation, and higher selectivity toward cancer cells as compared to normal cells than the corresponding free BODIPY photosensitizer. Conventional Ru(II) photoactivated complexes require nonbiorthogonal blue light for activation and rarely show submicromolar potency to achieve cell death. Our study represents an avenue for the improved photochemistry and potency of future Ru(II) complexes.

Assembly of Polyiodide Networks with Cu(II) Complexes of Pyridinol-Based Tetraaza Macrocycles.

Polyiodide networks are currently of great practical interest for the preparation of new electronic materials. The participation of metals in the formation of these networks is believed to improve their mechanical performance and thermal stability. Here we report the results on the construction of polyiodide networks obtained using Cu(II) complexes of a series of pyridinol-based tetraazacyclophanes as countercations. The assembly of these crystalline polyiodides takes place from aqueous solutions on the basis of similar structural elements, the [CuL]2+ and [Cu(H–1L)]+ (L = L2, L2-Me, L2-Me3) complex cations, so that the peculiarities induced by the increase of N-methylation of ligands, the structural variable of ligands, can be highlighted. First, solution equilibria involving ligands and complexes were analyzed (potentiometry, NMR, UV–vis, ITC). Then, the appropriate conditions could be selected to prepare polyiodides based on the above complex cations. Single-crystal XRD analysis showed that the coordination of pyridinol units to two metal ions is a prime feature of these ligands, leading to polymeric coordination chains of general formula {[Cu(H–1L)]}nn+ (L = L2-Me, L2-Me3). In the presence of the I–/I2 couple, the polymerization tendency stops with the formation of [(CuL)(CuH–1L)]3+ (L = L2-Me, L2-Me3) dimers which are surrounded by polyiodide networks. Moreover, coordination of the pyridinol group to two metal ions transforms the surface charge of the ring from negative to markedly positive, generating a suitable environment for the assembly of polyiodide anions, while N-methylation shifts the directional control of the assembly from H-bonds to I···I interactions. In fact, an extended concatenation of iodine atoms occurs around the complex dimeric cations, the supramolecular I···I interactions become shorter and shorter, fading into stronger forces dominated by the orbital overlap, which is promising for effective electronic materials.

Preoperative assessment of cervical lymph node metastases in patients with papillary thyroid carcinoma: Incremental diagnostic value of dual-energy CT combined with ultrasound.

PurposeTo determine whether dual-energy CT (DECT) has incremental diagnostic value when combined with ultrasound (US) in the diagnosis of metastatic cervical lymph nodes (LNs) in patients with papillary thyroid carcinoma (PTC).MethodsThis was a single-center retrospective cohort study of patients diagnosed with PTC between October 2019 and August 2020. US features of LNs to include hyperechogenicity, round shape, microcalcification, cystic component, and homogeneous/peripheral vascularity were considered suggestive of metastasis. The HU of arterial phase (HUarterial) and DECT-derived CT images [contrast media (CM) and areas under the 100 keV monoenergetic curve (AUC100keV)] were measured. Effective atomic numbers (Zeff), iodine concentration (mg/mL), and slope of the HU curve (λHU) were also obtained. The values for metastatic and benign LNs were compared using Student’s t-test with false-discovery correction. Logistic regression with areas under the receiver operating characteristic curves (AUCs) were performed for predicting metastatic LNs.ResultsA total of 102 patients were included (49 metastatic and 53 benign LNs; mean age, 46±15 years). Metastatic LNs showed significantly higher values for HUarterial, CM, Zeff, λHU, AUC100keV, and iodine concentration (all, P = 0.001). In logistic regression, the HUarterial demonstrated the highest AUC (0.824; 95% confidence interval [CI], 0.751–0.897), followed by CM HU (0.762; 95% CI, 0.679–0.846). Combination of DECT parameters with US features improved the AUC from 0.890 to 0.941.ConclusionCompared to US features alone, combination with DECT-derived quantitative parameters improved diagnostic performance in predicting metastatic cervical LNs in patients with PTC.

Spodium bonds and metal–halogen···halogen–metal interactions in propagation of monomeric units to dimeric or polymeric architectures

In this work we report on crystal structures of a heteroleptic coordination polymer [Hg2(HL)Cl4]n (1) where the nitrogen atom of the peripheral pyridine fragment is linked to another HgCl2 molecule and two discrete mononuclear heteroleptic complexes [Hg(HL)I2] (2) and [Mn(HL)Cl2]·MeOH (3·MeOH), which were obtained through self-assembling of N'-(1-(pyridin-2-yl)ethylidene)isonicotinohydrazide (HL) with HgCl2, HgI2 or MnCl2, respectively. HL coordinates the HgII salts in its keto-form, while MnCl2 is chelated by a zwitterionic form of HL confirmed by the solid state IR spectroscopy. The studied here ligand molecule has a tendency to involve the 4-pyridyl nitrogen atom in coordination bonding which is correlated with the ability to transfer the electric charge and production of a zwitterionic form. The crystal structure and Hirshfeld surface data analysis show a great importance of spodium bonds and metal–halogen⋯halogen–metal interactions. A prominent consequence of lack of σ- or π-hole interactions in case of MnII ion is the isolation of metal center from the external contacts. Apart form this in 3·MeOH the halogen⋯halogen interactions are absent. It seems that the σ- or π-hole regions formed at the HgII cation in 1 and 2 favor the participation of coordinated Cl or I atoms in the M–Hal⋯Hal'–M' halogen⋯halogen interactions, whereas in complex 3·MeOH there are no metal or halogen centered σ-hole interactions. Thus, the 1D coordination polymer in 1 is stabilized by the Hg⋯Cl spodium bonding. Additionally, the observed intermolecular halogen⋯halogen interactions in 1 provide cross-linking of the 1D coordination polymers, yielding a 2D supramolecular double-layered sheet. In 2 an additional contact between halogen and mercury atoms results in a dimeric unit. These dimers are linked into a 1D polymer by halogen⋯halogen interactions between metal bounded iodine atoms. The DFT theoretical studies were applied to analyze the Hg⋯X non-covalent spodium interactions that govern the formation of the 1D polymeric structure in 1 and self-assembled dimers in 2.

Red haloBODIPYs as theragnostic agents: The role of the substitution at meso position

Three different molecular designs based on BODIPY dye have been proposed as photosensitizers (PSs) for photodynamic therapy (PDT) by the inclusion of halogen atoms (Iodine) at 2,6-positions and with extended conjugation at 3, 5-positions and varying the substitution at meso position. The synthesis is described and their main photophysical features including singlet oxygen production and triplet states were characterized by absorption and fluorescence spectroscopy (steady-state and time-correlated) and nanosecond transient absorption spectroscopy. The results were compared with the commercial Chlorin e6. The three new red-halogen-BODIPYs showed a great balance between singlet oxygen generation (ΦΔ≥0.40) and fluorescence (Φfl≥0.22) for potential application on PDT, and particularly in theragnosis. In vitro experiments in HeLa cells were done to study their performance and to elucidate the best potential candidate for PDT.