Parent Ion Peak Research Articles

Synthesis, PXRD structure, spectroscopy, cyclic voltammogram, thermal analysis and DFT/TD-DFT calculations of bis[salicylaldehydato-κO,O']nickel(II)

The bis[salicylaldehydato-κO,O']nickel(II) (1) was synthesized from reaction of pyridyl-Schiff base ligands, N-2-(R1-pyridyl)salicylaldimine {R1 = H(HL1), 4-CH3 (HL2) and 6-CH3 (HL3)} and nickel(II) acetate via in-situ hydrolysis of the ligands back to the salicylaldehyde (HL'). The molecular structure of 1 was solved by PXRD which disclosed that the two molecules of O^O-chelate ligands formed a O2,O2-coordination sphere around the nickel atom with a square planar geometry. Elemental analysis data show no nitrogen atom in the sample. EI mass spectra exhibit the parent ion peak at m/z = 300. The molar conductance values (Λm = 2.08–2.15 S m2 mol−1) endorse non-electrolyte nature of 1 with metal-to-ligands ratio of 1:2 in DMF. Solid-state magnetic moment value (μeff. = 3.00 μB) suggests paramagnetic nature of the high-spin nickel(II) complex, supported by 1H NMR, UV–vis. (experimental and simulated spectra) and optimized and PXRD structures. DSC analysis recommends an irreversible phase transformation from crystalline-solid to solid–liquid and isotropic-liquid phase. Cyclic voltammograms demonstrate an irreversible one electron charge transfer process for [Ni(L')2]0/[Ni(L')2]− (L' = salicylaldehydato) couple in acetonitrile. Optimized structures and excited state properties by DFT/TD-DFT correspond well to PXRD structure and electronic spectra in solution.

Pseudotetrahedral high-spin manganese(II)-complexes with (S or R)-N-1-(Ar)ethyl-salicylaldimine: Chiroptical property, chirality induction at-metal, paramagnetism, redox-potential, PXRD structures and DFT/TDDFT

Pseudotetrahedral high-spin bis[(S or R)-N-1-(Ar)ethyl-salicylaldiminato-κ2N,O]-Λ/Δ-Mn(II) {Ar = C6H5 (MnSL1 or MnRL1), p-MeOC6H4 (MnSL2 or MnRL2) and p-BrC6H4 (MnSL3 or MnRL3)} are synthesized from reactions between enantiopure Schiff base ligands (S or R)-N-1-(Ar)ethyl-salicylaldimine and manganese(II) chloride with induction of Λ/Δ-chirality-at-metal. ESI mass spectra show the parent ion peak for the mononuclear species at m/z 504 (MnRL1 or MnSL1) and 662 (MnSL3 or MnRL3). The molar conductance values imply mononuclear and non-electrolyte nature of the complexes with metal-to-ligand 1:2 stoichiometry in dimethylformamide (DMF). Electronic circular dichroism (ECD) spectra exhibit mirror-image relationships, and hence confirm enantiopurity or enantiomeric excess of the R- or S-ligated complexes in solution. It suggests the diastereomer or diastereomeric excess of Δ-MnRL or Λ-MnSL in solution combined with the analyses on experimental and simulated ECD spectra by Density Functional Theory/Time-dependant Density Functional Theory (DFT/TDDFT), resulting from diastereoselectively induced Δ- or Λ-chiralityat-metal. In the contrast, DFT optimized structures in gas-phase disclose Λ-MnRL or Δ-MnSL diastereomer slightly more stable than Δ-MnRL or Λ-MnSL by 2–4 kcal/mol. Variable temperature magnetic moment values (μeff. = 5.25−5.55 μB at 263−321 K) correspond to the high-spin state of Mn(II)-complexes in methanol. Cyclic voltammograms demonstrate two one electron charge transfer processes for MnIII/II and MnII/I couples in acetonitrile, respectively. Powder XRD patterns reveal a well-defined crystalline nature and allow structure determination for the MnRL3, using the Expo-2014 program followed by Rietveld refinement. PXRD structure suggests the formation of four-coordinated mononuclear manganese(II)-complex by the two phenolate-oxygen and two imine-nitrogen atoms from two molecules of Schiff base ligands in a pseudotetrahedral geometry.

Isolation Of Anticancer Drug Taxol Producing Endophytic Fungus Alternaria Alternata By Using HPLC And LC- MS

Abstract Introduction/Objective In the exploration of an alternative source, optimum and numerous solvents with different percentage were exploited to extract Taxol from plant palm branche. The fungal endophytes producing secondary metabolites that are effective against the human infections have fascinated many researchers across the world. Among these, the exploration for novel cancer therapeutic agents is of countless reputation due to upsurge in the number of cancer deaths, high worth of the drugs and the side effects concomitant with cancer treatments. Accordingly, in the current study, an endophytic fungal strain was isolated from its host plant palm branche and identified as Alternaria Alternata based on its morphological features and internal transcribed spacer sequence analysis. Methods Firstly, palm branche were collected for the isolation of endophytic fungi. The samples were placed on PDA plates and after 72 h, the mycelium produced were isolated and sub-cultured. Secondly, further analysis for the presence of Taxol by using chromatographic and spectrometric techniques. Illustratively, ethanol or acetone and 50% and 20% of ethanol. Then, the residues were dissolved in 5 ml of methanol and filtered. By using the internal standard, the resulting solution was subjected to the HPLC to determine the extraction efficiencies of tested solvents. Finally, filtrate was also subjected to the LC-MS – ESI using water/acetonitrile (10/90) as mobile phase to identify the authenticity of Taxol Results HPLC analysis revealed that Taxol could be quantified by UV detection using standard curve. Furthermore, the standard curve covering the concentration was linear (r2= 0.9992) and CV% ranged from 0.52 to 15.36. The peaks of fraction 5 obtained by HPLC analysis were quite similar to that of standard taxol confirming the presence of taxol. A parent ion peak of m/z 851.85 was observed in the LC–ESI–MS spectrum which was similar to paclitaxel with reported m/z of 854 [M+H] + ion. A. Alternata produced about 113.193 mg/L taxol as quantified through HPLC Conclusion we are recording for the first time the production of taxol by an endophytic fungus Alternaria Alternata. In a final word, present study results advocate that the endophytic fungus A.Alternata aids as a potential source for the production of taxol isolated from Palm branche plant

Isolation of taxol producing endophytic fungus Alternaria brassicicola from non-Taxus medicinal plant Terminalia arjuna.

In the present study, an endophytic fungal strain was isolated from its non-Taxus host plant Terminalia arjuna and identified as Alternaria brassicicola based on its morphological characteristics and internal transcribed spacer sequence analysis. This fungus was grown in potato dextrose broth and analyzed for the presence of taxol by using chromatographic and spectrometric techniques. The ethyl acetate extract of A.brassicicola was subjected to column chromatography. Among the different fractions, the fraction 7 showed positive to taxol, which was further confirmed by UV absorption, HPLC, FTIR spectra and LC-ESI-MS by comparing with the authentic taxol (Paclitaxel). The peaks of fraction 7 obtained by UV spectroscopy, FTIR and HPLC analysis were quite similar to that of standard taxol confirming the presence of taxol. A parent ion peak of m/z 854.95 was observed in the LC-ESI-MS spectrum which was similar to paclitaxel with reported m/z of 854 [M+H]+ ion. A. brassicicola produced about 140.8μg/l taxol as quantified through HPLC. Present study results suggest that the endophytic fungus A.brassicicola serves as a potential source for the production of taxol isolated from non-Taxus plant.

Target separation of flavonoids from Saxifraga tangutica using two-dimensional hydrophilic interaction chromatography/reversed-phase liquid chromatography.

An orthogonally (80.3%) preparative two-dimensional hydrophilic interaction chromatography/reversed-phase liquid chromatography method has been established for the isolation and purification of flavonoids from Saxifraga tangutica. Initially, flavonoids were enriched by means of a middle-pressure chromatographic tower (containing middle chromatogram isolated gel). In the first dimension, a XION preparative column was used to separate the flavonoid fractions under the guidance of characteristic ultraviolet absorption spectra of flavonoids and nine flavonoid fractions were obtained. Then, the coeluted flavonoid fractions were selected for further purification via reversed-phase liquid chromatography with the parent ion peak of quercetin (303), kaempferol (287), or isorhamnetin (317). Several flavonoids could be separated from each hydrophilic interaction chromatography fraction; furthermore, flavonoids with poor resolution in one-dimensional liquid chromatography were isolated in two-dimensional liquid chromatography due to the orthogonality. In addition, this technique was valuable for trace flavonoids, which were concentrated in the first stage and separated in the second stage. In total, 18 flavonoids with either quercetin, kaempferol, or isorhamnetin parent nuclei were targetedly obtained, and 15 flavonoids were obtained for the first time from S. tangutica. These results established that the off-line two-dimensional hydrophilic interaction chromatography/reversed-phase liquid chromatography technique was efficient for the isolation of flavonoids from Saxifraga tangutica.

질량분석 시스템을 이용한 극지 토양 유래 신규 미생물의 지질 A 화학적 구조 분석

For decades, the microorganisms in arctic soils have been newly discovered according to the climate change and global warming. In this study, the chemical structure of a lipid A molecule from Pseudomonas sp. strain PAMC 28615 which was newly discovered from arctic soils was characterized by mass spectrometric approaches such as matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) and MALDI multi-stage tandem mass spectrometry (MS). First, lipopolysaccharide (LPS) from Pseudomonas sp. strain PAMC 28615 was extracted and subsequently hydrolyzed to obtain the lipid A. The parent ion peak at m/z 1632 was determined by MALDI-TOF MS, which also can validate our lipid A purification method. For detailed structural determination, we performed the multiple-stage tandem mass analysis (<TEX>$MS^4$</TEX>) of the parent ion, and subsequently the abundant fragment ions in each MS stage are tested. The fragment ions in each MS stage were produced from the loss of phosphate groups and fatty acyl groups, which could be used to confirm the composition or the position of the lipid A components. Consequently, the mass spectrometry-based lipid A profiling method could provide the detail chemical structure of lipid A from the Pseudomonas sp. strain PAMC 28615 as an arctic bacterium from the frozen arctic soil.

Extraction and Analysis of Ketamine (a Rave Drug) from Spiked Fruit Juices Using MEPS-MS for Forensic Purposes

Micro extraction packed sorbent (MEPS) containing C8 and SCX (strong cation exchange) is employed to extract ketamine, a rave drug from fruit juices. The eluant was detected by mass spectral analysis wherein the drug was detected as a parent as well as some prominent fragment ions. The resultant MEPS-MS method proved very efficient and rapid. The mass spectrum of the eluant showed the parent ion peak (MH + ) of ketamine at m/z 238 along with (MH 2+ ) peak (30% of MH + ) due to chlorine atom in the drug molecule. The daughter ions at m/z 220 and 207 were possible to be formed from the MH + by loss of water and methylamine molecule respectively. Another daughter ion at m/z 179 was proposed to be formed by the loss of CO (28 mass units) from m/z 207 whereas m/z 125 was assigned to a chlorobenzyl cation. Based on the mode of fragmentation of drug to m/z 220 and 207 and their abundances, these ions can be used for quantitative analysis through selective reaction monitoring (SRM).

Generation of a Dynamic System of Three‐Dimensional Tetrahedral Polycatenanes

Generation of a Dynamic System of Three‐Dimensional Tetrahedral Polycatenanes

Quantitative determination of phorbol ester derivatives in Chinese Jatropha curcas seeds by high-performance liquid chromatography/mass spectrometry

Phorbol esters (PEs) are the main toxins in Jatropha curcas seeds and known to cause a wide range of biological effects. In this study, we investigated PE derivatives in Chinese J. curcas seeds by high-performance liquid chromatography/mass spectrometry. Five PE peaks were detected, and all of them presented a parent ion peak [M−H]−m/z 709.8 in the mass spectrum which were consistent with previous reports that PE derivatives shared a similar parental backbone. According to the mass spectra data and the retention time, the existence of six PE derivatives named C1–C6 in Chinese J. curcas seeds was confirmed in our study. The content of phorbol ester derivatives in the seeds from six geographic locations in China were ranging 1.098–2.417mgg−1. In addition, our results indicated that the contents of the different PE derivatives were closely correlated to the geographic locations of seeds. Seeds from Yunnan contained more derivative C1 but fewer C2 and C5, whereas seeds from Sichuan contained more C2 and C5 but fewer C1 derivative. Our results suggested that variations in PE derivatives might be used as markers to infer the geographic information of J. curcas seeds.

The Single- and Double-Strand Cleavage of DNA by a Cationic Dicobalt Complex by Visible Light

Abstract A one-pot synthesis of a new polycationic organo–dicobalt complex having dual cationic alkyl groups as radical sources is reported. The complex was characterized by elemental analysis, UV–vis, 1H NMR, IR, and CSI-mass spectroscopies. CSI-MS afforded intact parent ion peak with labile cobalt–carbon bonds in the complex. The complex was photosensitive, and photocleavage of the cobalt–carbon bonds upon irradiation with visible light produced dual cationic carbon-centered radicals that were detected by EPR spin-trapping. Strong binding of the dicobalt complex with six cationic moieties toward DNA was confirmed by ethidium bromide displacement assays with Kapp = 3.2 × 107 M−1 at 298 K, the value was 100 times that of corresponding monocobalt complex with Kapp = 3.3 × 105 M−1. The dicobalt complex exhibited high ability for single- and double-strand DNA cleavage in comparison with that for the corresponding monocobalt complex under irradiation with visible light.

A systematic investigation of the CuCl 2/H 2mal/phen reaction system (H 2mal = malonic acid): Solution and solid state studies of its products

The systematic investigation of the parameter space of the CuCl 2/H 2mal/phen reaction system in MeOH resulted in the isolation of seven different complexes either as mixtures or in pure form, six of which have been structurally characterized. The molar ratios of the reactants and the crystallization methods have been systematically varied, leading to the isolation of compounds [Cu(H 2O)(phen)(mal)] ( 1), [Cu(MeOH)(phen)(mal)] ( 2), [Cu 2Li 2Cl 2(phen) 2(mal) 2(MeOH) 4] ( 3), [Cu 2(phen) 4(mal)][CuCl(phen)(mal)](OH) ( 4), [CuCl(phen) 2]Cl ( 5), and [CuCl(phen)(mal)][CuCl(phen) 2][Cu(phen) 2(Hmal)]Cl ( 6). The coordination versatility of the malonato ligand has been confirmed by the presence of three different coordination modes and its two deprotonation states in compounds 1– 6. Solution studies on methanolic solutions of 2– 4 and 6 by mass spectrometry revealed the absence of parent ion peak and the presence of fragment ions of low relative abundance not previously found in their crystal structure, thus indicating decomposition and rearrangement/reorganization of the complexes in solution and confirming the dynamic character of their solutions. Compounds 3 and 4 have been also studied in the solid state by EPR spectroscopy and magnetic measurements.

Effect of Cation Absorption on Ionization/Dissociation of Cycloketone Molecules in a Femtosecond Laser Field

The mass spectra of a series of cycloketone molecules, cyclopentanone (CPO), cyclohexanone (CHO), cycloheptanone (CHPO), and cyclooctanone (COO) are measured in a 788 or 394 nm laser field with 90 fs pulse duration and the intensity ranging from 5 x 10(13) W/cm(2) to 2 x 10(14) W/cm(2). At 788 nm, a dominated parent ion peak and some weak peaks from the fragment ions C(n)H(m)+ are observed for CPO and CHO (a ratio P(+)/T(+), the parent ion yield to the total ion yield, is 81.6% and 52.6%, respectively). But the extensive fragment ion peaks are observed with the greatly reduced parent ion peak for CHPO (P(+)/T(+) = 5.5%) and that are even hard to be identified for COO. These observations are interpreted explicitly in the frame of the significant resonant effect of their cation photoabsorption on ionization and dissociation of these molecules. The present work also suggests that a nonadiabatic ionization occurs with a nuclear rearrangement due to the H movement in these molecules during the ionization in an intense femtosecond laser field.

Carbon−Sulfur Bond Formation via Alkene Addition to an Oxidized Ruthenium Thiolate

Bulk oxidation of [Ru(DPPBT)3], 1b, (DPPBT = 2-diphenylphosphinobenzenethiolate) in the presence of ethylene yields [(ethane-1,2-diylbis(thio-2,1-phenylene)diphenylphosphine) ruthenium(II)] hexafluorophosphate, [2a]PF6, from the addition of the alkene across cis sulfur sites. During oxidation, the absorption bands of 1b at 540, 797, and 1041 nm decrease in intensity. The resulting complex [2a]+ displays a single redox couple at +804 mV. The +ESI-MS of [2a]+ shows a parent ion peak at m/z = 1009.1013, and the 31P NMR spectrum displays chemical shift values of delta(1) = 61.0, delta(2) = 40.3, and delta(3) = 37.5 with coupling constants of J(12) approximately J(13) approximately 30 Hz and J(23) = 304 Hz. Oxidation of [2a]+ by one electron at a holding potential of +1000 mV yields [(ethane-1,2-diylbis(thio-2,1-phenylene)diphenyl phosphine)ruthenium(III)] hexafluorophosphate, [2b][PF6]2. The EPR of [2b][PF6]2 displays a rhombic signal with g(1) = 2.09, g(2) = 2.04, and g(3) = 2.03. Oxidation of 1b in the presence of alkenes including 1-hexene, styrene, cyclohexene, and norbornene yields products similar to [2a]+. Each of these products was further oxidized to an analogue of [2b]2+. Complex [2a]+ was also prepared, as the bromide salt, from [PPN][Ru(DPPBT)3] (PPN [1a]; PPN = bis(triphenylphosphoranylidene)ammonium) and 1,2-dibromoethane. The complex [2a]Br crystallizes as thin yellow plates in the monoclinic space group P21/c with unit cell dimensions of a = 10.2565(9) A, b = 13.2338(12) A, c = 38.325(3) A, and beta = 93.3960(10) degrees.

Determination of three major triterpenoids in epicuticular wax of cabbage ( Brassica oleracea L.) by high-performance liquid chromatography with UV and mass spectrometric detection

Lupeol, together with α- and β-amyrins in smaller quantities, has been found for the first time in the epicuticular wax of white cabbage ( Brassica oleracea L. convar. capitata (L.) Alef. var. alba DC) leaf surface extract. The three triterpenoids were identified by a new high-performance liquid chromatographic (HPLC) method with UV and mass spectrometric (MS) detection using atmospheric pressure chemical ionization (APCI). All three isomeric compounds gave a parent ion peak at m/ z 409 [ M + H-18] + and the relative intensities of some characteristic fragment ion peaks in tandem mass spectrometric (MS–MS) spectra of this parent ion enabled differentiation between the isomers. An additional peak at m/ z 439 [ M + H] +, which could be oleanonic or ursonic aldehyde, was detected by HPLC–APCI–MS. Saponification of cabbage leaf surface extract with 20% NaOH in methanol at 65 °C for 2 h had no influence on lupeol, or α- or β-amyrins, but lead to the formation of three additional compounds, which were not identified.

The electron affinity of phenanthrene

Phenanthrene is studied by photodetachment-photoelectron spectroscopy. Due to the absence of a parent ion peak in the anion mass spectrum the electron affinity could not be determined directly. However, this absence is the first indication that this molecule has a negative electron affinity. The first three water complexes of phenanthrene were studied, supplying insights into its microsolvation property. Moreover, the electron affinity of the bare molecule could be determined to be -0.01+/-0.04 eV by an extrapolation method using the water cluster data. The experimental work is supported by ab initio calculations for determining the structure of the water complexes. Finally a correlation between the electron affinity and the reduction potential of polycyclic aromatic hydrocarbons is investigated.

Thermal Vaporization of Biological Nanoparticles: Fragment-Free Vacuum Ultraviolet Photoionization Mass Spectra of Tryptophan, Phenylalanine−Glycine−Glycine, and β-Carotene

A simple, new way to introduce fragile biomolecules into the gas phase via thermal vaporization of nanoparticles is described. The general utility of this technique for the study of biomolecules is demonstrated by coupling this source to tunable synchrotron vacuum ultraviolet radiation. Fragment-free photoionization mass spectra of tryptophan, phenylalanine-glycine-glycine, and beta-carotene are detected with signal-to-noise ratios exceeding 100. The 8.0 eV photoionization mass spectrum of tryptophan nanoparticles vaporized at 373 K is dominated by a single parent ion peak that exhibits a 20-fold enhancement over the methylene indole fragment ion. The degree of dissociative photoionization of tryptophan can be precisely controlled either by the thermal energy imparted into the neutral tryptophan molecule or by the energy of the ionizing photon. The results reveal how approximately 0.5 eV changes in internal energy affect both the photoionization mass spectrum of tryptophan and the appearance energy of the daughter ion fragments. This method allows the ionization energies of glycine (9.3 +/- 0.1 eV), tryptophan (7.3 +/- 0.2 eV), phenylalanine (8.6 +/- 0.1 eV), phenylalanine-glycine-glycine (9.1 +/- 0.1 eV), and beta-carotene (<7.0 eV) molecules to be determined directly from the photoionization efficiency spectra.

Laser induced photodissociation of CH 2Cl 2 and CH 2Br 2 at 355 nm: an experimental and theoretical study

Experimental and theoretical studies have been carried out for nanosecond 355 nm laser induced dissociation/ionisation of dihalomethanes (CH 2Cl 2 and CH 2Br 2) using time of flight mass spectrometer. Both the molecules follow quite similar ionisation pattern and mass spectra showed H +, CH 2 +, X +, CX +, and CH 2X + as major ions with absence of parent ion peak. The energetics of different dissociation channels in the ground state of CH 2X +/CH 2X systems was investigated using ab initio calculations. Proposed mechanism involves dissociation of CH 2X 2 into CH 2X, which then dissociates into several distinct competitive channels, products of which are subsequently ionised.

A novel heptasialosyl c-series ganglioside in embryonic chicken brain: its structure and stage-specific expression

A ganglioside of unknown structure (ganglioside X) was purified from chicken brain at embryonic day 12 (E12) and characterized for its structure. Ganglioside X was reactive with a monoclonal antibody A2B5 and migrated below GH1c on thin-layer chromatography (TLC). Extensive treatment of ganglioside X with Clostridium perfringens sialidase produced a single ganglioside product. This ganglioside was identified as GM1 based upon its chromatographic mobility and reactivity to cholera toxin B subunit and anti-GM1 antibody. Partial hydrolysis of ganglioside X by sialidase generated several degradation products including GH1c, GP1c, and GQ1c. Electrospray ionization (ESI)-mass spectrometry (MS) of the permethylated derivative of ganglioside X produced a triple-charged parent ion peak at m/ z 1355, which corresponded with the gangliotetraose oligosaccharide structure having seven sialic acids and ceramide with the molecular mass of 566 (as non-methylated form). Collision-induced dissociation (CID)-MS 2 showed fragment ions including those at m/ z 1066 and 1931; these two ions matched the structures of (NeuAc) 3-Gal-Glc-Cer and (NeuAc) 4-Gal-GalNAc, respectively. These structures were confirmed by CID-MS 3 of the corresponding peaks. Based upon these findings, the structure of ganglioside X was identified as NeuAc-NeuAc-NeuAc-NeuAc-Galβ1–3GalNAcβ1–4(NeuAc-NeuAc-NeuAcα2–3)Galβ1–4Glcβ1-1′Cer. This ganglioside was designated as GS1c. A developmental study demonstrated that GS1c was expressed in chicken brain during a period from E6 to E13 and thereafter decreased rapidly in its concentration. The present study suggests that GS1c may play a specific role in early development of chicken brain.

Thermal vaporization-vacuum ultraviolet laser ionization time-of-flight mass spectrometry of single aerosol particles.

Single aerosol particles of ethylene glycol and oleic acid are vaporized on a heater at temperatures between 500 and 700 K, and the resulting vapor plume is ionized by a 10.5-eV vacuum ultraviolet (VUV) laser. The mass spectra are compared to those obtained by CO2 laser vaporization followed by VUV laser ionization. The relative intensities of the parent and fragment ion peaks are remarkably similar for the two modes of vaporization. A Maxwell-Boltzmann distribution of speeds accurately describes the dependence of the signal as a function of the VUV laser pulse timing. The signal levels obtained with this design are sufficient to obtain good-quality mass spectra.

Femtosecond laser mass spectroscopy of ferrocenes: photochemical stabilization by bridged cyclopentadienyl rings?

We present time-of-flight mass spectra of ferrocene measured with 200 fs UV laser pulses at various wavelengths. As a striking result, strong parent ion peaks and FeCp + fragments are observed in the femtosecond experiment while in the nanosecond mass spectra only Fe + fragment peaks have been detected. The latter is ascribed to a fast dissociation of neutral ferrocene after absorption of the first photon. Excitation with femtosecond pulses favors further photon absorption and ionization. The measured fragmentation patterns are explained by an energetic model assuming switching of absorption from the neutral molecule to the ion as soon as the ionization energy is reached. The bridging of the two Cp rings in [3]-ferrocenophan seems to stabilize the cation but does not suppress the fast production of Fe from electronically excited neutral molecules.