Cis Isomerization Research Articles

Rational design and synthesis of a task-specific porous organic framework featured azobenzene as a photoresponsive low-energy CO2 adsorbent

An azobenzene-containing porous organic framework (POF) was rationally designed and synthesized via Sonogashira-Hagihara coupling reaction. By virtue of high porous skeleton and azobenzene as light responsive group, this task-specific POF exhibits the reversible stimuli-responsive adsorption property triggered by UV irradiation and heat treatment. The initial Brunauer-Emmet-Teller (BET) surface area of this porous material is 571 ​m2 ​g−1, while the BET surface area after UV irradiation decreases to 550 ​m2 ​g−1 along with the reduction of micropores around 0.5 ​nm and 1.3 ​nm during the trans to cis isomerization process. Furthermore, CO2 sorption isotherms show a slight decrease, which is caused by the trans to cis conversion of azobenzene side group. It is worth mentioning that CO2 uptakes of POFs are almost constant for three cycles via alternating external stimuli to confirm the excellently reversible switchability of trans-to-cis isomerization.

A bidirectionally reversible light-responsive actuator based on shape memory polyurethane bilayer

In this work, a simple method is proposed for the preparation of bidirectionally reversible light-responsive shape memory polyurethane (SMPU) bilayer. This SMPU bilayer consists of a 4,4-azodibenzoic acid (Azoa) containing SMPU (SMPU-Azoa) layer and a carbon black (CB) containing SMPU (SMPU-CB) layer. A reversible deformation is realized when the two sides are exposed to ultraviolet (UV) and infrared (IR) lights, respectively. The working mechanism is the trans–cis isomerization of SMPU-Azoa layer and the photo-thermal effect of SMPU-CB layer. The effect of the filler content and the thickness ratio of bilayer is systematically studied. The reversible bending angle of the SMPU bilayer can exceed 30° in 16 s for one cycle when the Azoa and CB contents are 5 wt% and 0.5 wt%, respectively, and the thickness ratio of SMPU-Azoa layer to SMPU-CB layer is 1/1.3. Furthermore, a micro-robot based on such LSMP bilayer is demonstrated.

Simultaneous Incorporation of Two Types of Azo-Groups in the Side Chains of a Conjugated D-A Polymer for Logic Control of the Semiconducting Performance by Light Irradiation.

A new design strategy for photoresponsive semiconducting polymer with tri-stable semiconducting states is reported by simultaneous incorporation of tetra-ortho-methoxy-substituted azobenzene (mAzo) and arylazopyrazole (pAzo) in the side chains. The trans-to-cis transformations for mAzo and pAzo groups can sequentially occur within the polymer thin film after sequential 560 and 365nm light irradiation. Remarkably, the trans-cis isomerization of mAzo and pAzo groups can modulate the thin film crystallinity. Accordingly, the performances of the resulting field-effect transistors (FETs) can be reversibly modulated, leading to tri-stable semiconducting states after sequential 560, 365, and 470nm light irradiation. Therefore, the device performance can be logically controlled by light irradiation at three different wavelengths. In addition, with light irradiation and device current as the input and output signals, the three-value logic gate by using single FET device can be successfully mimicked.

Theoretical mechanistic study on the reaction of the methoxymethyl radical with nitrogen dioxide.

Mechanism of the reaction of CH3OCH2 with NO2 is explored theoretically at the M062X/MG3S and G4 levels. The calculated results indicate two stable association intermediates, CH3OCH2NO2 (IM1) and CH3OCH2ONO (IM2), which can be produced by the attack of the nitrogen or oxygen atom of NO2 to terminal carbon atom of CH3OCH2 without barrier involved. IM2 is found to take trans (IM2a)-cis (IM2b) conversion and isomerization to IM1, with the following stability order IM2a > IM2b > IM1. Starting from IM2a, the most feasible pathway is the direct O-NO bond cleavage leading to P1 (CH3OCH2O + NO) or the H-shift and O-NO bond rupture to produce P2 (CH3OCHO + HNO), both of which have comparable contribution to the title reaction. There also involves an H-transfer from the methyl group of IM2a to the N atom with the simultaneous dissociations of the C-O and O-N bonds to produce P4 (2CH2O + HNO). In addition, another dissociation pathway is open to IM2b which decompose to P5 (CH2O + CH3ONO) by the O-N and C-O bond scissions and the recombination of CH3O and NO. Because all the intermediates and transition states involved in the above pathways lie below reactants, the CH3OCH2 + NO2 reaction is expected to be rapid. Subsequent dissociation of IM1 and direct H-abstraction between CH3OCH2 and NO2 are kinetically almost inhibited due to significantly high barriers. The present results can lead us to deeply understand the mechanism of the title reaction and may be helpful for understanding NO2 combustion chemistry.

Structure of a retinal chromophore of dark-adapted middle rhodopsin as studied by solid-state nuclear magnetic resonance spectroscopy.

Middle rhodopsin (MR) found from the archaeon Haloquadratum walsbyi is evolutionarily located between two different types of rhodopsins, bacteriorhodopsin (BR) and sensory rhodopsin II (SRII). Some isomers of the chromophore retinal and the photochemical reaction of MR are markedly different from those of BR and SRII. In this study, to obtain the structural information regarding its active center (i.e., retinal), we subjected MR embedded in lipid bilayers to solid-state magic-angle spinning nuclear magnetic resonance (NMR) spectroscopy. The analysis of the isotropic 13C chemical shifts of the retinal chromophore revealed the presence of three types of retinal configurations of dark-adapted MR: (13-trans, 15-anti (all-trans)), (13-cis, 15-syn), and 11-cis isomers. The higher field resonance of the 20-C methyl carbon in the all-trans retinal suggested that Trp182 in MR has an orientation that is different from that in other microbial rhodopsins, owing to the changes in steric hindrance associated with the 20-C methyl group in retinal. 13Cζ signals of Tyr185 in MR for all-trans and 13-cis, 15-syn isomers were discretely observed, representing the difference in the hydrogen bond strength of Tyr185. Further, 15N NMR analysis of the protonated Schiff base corresponding to the all-trans and 13-cis, 15-syn isomers in MR showed a strong electrostatic interaction with the counter ion. Therefore, the resulting structural information exhibited the property of stable retinal conformations of dark-adapted MR.

9-cis and all-trans beta-carotene isomers of super critical CO2-extracted Dunaliella oil are absorbed and accumulated in mouse tissues

ABSTRACT Animals cannot produce β-carotene, and therefore they exclusively depend on its dietary availability. We previously showed that a 9-cis β-carotene-enriched diet, provided as Dunaliella powder, has a beneficial effect on atherosclerosis and diabetes mellitus in animal models and on lipid profiles, retinitis pigmentosa, and psoriasis in human trials. Therefore, the current study aimed to investigate the bioavailability of 9-cis β-carotene from super-critical CO2-extracted Dunaliella oil in mice. In total, ten 12-week old mice were allocated into two groups: (1) a control-received unfortified diet; (2) a Dunaliella oil diet enriched with Dunaliella oil. Four-week dietary supplementation with Dunaliella oil led to a substantial accumulation of both all-trans and 9-cis β-carotene in the plasma, liver and white adipose tissue. β-carotene was stable in oil preparation, and the 9-cis to all-trans β-carotene ratio was constant (60:40, g/g) after two years of storage at 4°C. These results suggest that supercritically extracted Dunaliella oil can potentially be used as a food supplement.

Substitution effect on the nonradiative decay and trans → cis photoisomerization route: a guideline to develop efficient cinnamate-based sunscreens.

Cinnamate derivatives are very useful as UV protectors in nature and as sunscreen reagents in daily life. They convert harmful UV energy to thermal energy through effective nonradiative decay (NRD) including trans → cis photoisomerization. However, the mechanism is not simple because different photoisomeirzation routes have been observed for different substituted cinnamates. Here, we theoretically examined the substitution effects at the phenyl ring of methylcinnamate (MC), a non-substituted cinnamate, on the electronic structure and the NRD route involving trans → cis isomerization based on time-dependent density functional theory. A systematic reaction pathway search using the single-component artificial force-induced reaction method shows that the very efficient photoisomerization route of MC can be essentially described as "1ππ* (trans) → 1nπ* → T1 (3ππ*) → S0 (trans or cis)". We found that for efficient 1ππ* (trans) → 1nπ* internal conversion (IC), MC should have the substituent at the appropriate position of the phenyl ring to stabilize the highest occupied π orbital. Substitution at the para position of MC slightly lowers the 1ππ* state energy and photoisomerization occurs via a slightly less efficient "1ππ* (trans) → 3nπ* → T1 (3ππ*) → S0 (trans or cis)" pathway. Substitution at the meta or ortho positions of MC significantly lowers the 1ππ* state energy so that the energy barrier of IC (1ππ* → 1nπ*) becomes very high. This substitution leads to a much longer 1ππ* state lifetime than that of MC and para-substituted MC, and a change in the dominant photoisomerization route to "1ππ* (trans) → C[double bond, length as m-dash]C bond twisting on 1ππ* → S0 (trans or cis)". As a whole, the "1ππ* → 1nπ*" IC observed in MC is the most important initial step for the rapid change of UV energy to thermal energy. We also found that the stabilization of the π orbital (i) minimizes the energy gap between 1ππ* and 1nπ* at the 1ππ* minimum and (ii) makes the 0-0 level of 1ππ* higher than 1nπ* as observed in MC. These MC-like relationships between the 1ππ* and 1nπ* energies should be ideal to maximize the "1ππ* → 1nπ*" IC rate constant according to Marcus theory.

Unraveling the surface properties of PMMA/azobenzene blends as coating films with photoreversible surface polarity.

Various reports demonstrated that azobenzene derivatives are the chromophore of choice in photoresponsive surfaces showing reversible surface polarity. Hitherto the surface study of coating films based on polymer/azobenzene blends using contact angle measurements remained unexplored. To provide insight into the surface polarity of polymer/dye blend films, poly(methyl methacrylate) (PMMA) blends containing photoresponsive 4-hydroxy-4′-methylazobenzene (AZO1) and 4,4′-dimethylazobenzene (AZO2) as coating films on clear glass substrates are investigated in this work. Contact angle measurements were carried out to unravel the role of substituents in the surface polarity and the orientation of chromophores in the coating matrices before and after UV light (λmax = 365 nm) irradiation. Changes in water contact angles measured on the PMMA/azobenzene coating films indicated that the surface polarity is reversible as the chromophores underwent reversible trans–cis isomerisation. It has been revealed that the repeated trans–cis isomerisation led to the random reorientation and arrangement of chromophores in PMMA/AZO1 coating films. Then, to indicate the possibility of the disruption of interfacial interactions due to the repeated trans–cis isomerisation processes, as a proof of concept experiment, it is shown that the commercial acrylic-based pressure-sensitive sticker which adhered strongly to the PMMA/AZO1(13) coating film is peeled off from the coating surface after being subjected to a cycle of UV light irradiation for 12 hours, followed by dark conditions for another 12 hours within 14 days. The proof of concept study will lead to more development of smart photoresponsive coating films using simple polymer/dye blends.

Geometrically isomeric Pt2Ag2 acetylide complexes of 2,6-bis(diphenylphosphino)pyridine: luminescent and vapochromic properties

Geometrically isomeric cis- and trans-Pt2Ag2 alkynyl complexes are characterized by X-ray crystallography with trans-isomers showing bright phosphorescence and interesting vaporchromic properties.

Experimental study of the [ZnCl2(THF)2] catalyzed cis/trans-isomerization of [Pd(C6Cl2F3)Me(PPh3)2] and of the transmetalation of trans-[PdCl(C6Cl2F3)(PPh3)2] with [ZnMeCl(THF)2

The kinetics of the transmetalation reaction between trans-[PdCl(C6Cl2F3)(PPh3)2] and [ZnMeCl(THF)2] shows a complex dependence on [PPh3] for the rate of formation of different reaction products: cis and trans-[Pd(C6Cl2F3)Me(PPh3)2], trans-[PdClMe(PPh3)] (which further reacts with [ZnClMe(THF)2]), and [Zn(C6Cl2F3)Cl(THF)2]. To better understand the system the reactions between cis and trans-[Pd(C6Cl2F3)Me(PPh3)2] and [ZnCl2(THF)2] (the retro-transmetalation reactions) and their kinetic dependence on [PPh3] were studied. These reactions lead to the formation of trans-[PdClMe(PPh3)] and [Zn(C6Cl2F3)Cl(THF)2] as main products. Additionally, the experiments show that the isomerization of cis to trans-[Pd(C6Cl2F3)Me(PPh3)2] is catalyzed by [ZnCl2(THF)2]. In this catalyzed isomerization the concentration of PPh3 is involved in two ways: It modulates the concentration of the organozinc [Zn(C6Cl2F3)Cl(THF)2], and also it shifts a ligand substitution equilibrium in the palladium complex, producing an anomalous dependence of the reaction rate on the concentration of triphenylphosphine.

Isomerism, conformation, and structure of Bis(4,4-dimethyl-1-phenylpentane-1,3-dionato)copper(II); A theoretical and spectroscopy approach

Cis and trans isomerism, conformers, molecular structure, relative energies, spectroscopic analysis, metal-ligand strength, and complete vibrational assignment of bis(4,4-dimethyl-1-phenylpentane-1,3-dionato) copper (II), Cu(dmpd)2, were investigated by applying calculated parameters such as density functional theory (DFT), Atoms in Molecules (AIM) study at the B3LYP/6-311G(d) level of theory and experimental techniques contains of vibrational spectra and UV spectroscopy. A comprehensive assignment of the experimental bands of Cu(dmpd)2 has been done. The DFT and spectroscopy techniques applied to consider the assessment of methyl and phenyl and t-But substituents in the β-position on the geometrical and vibrational analysis of complexes. So, the structure, Cu-O strength of the complex, UV spectrum, and vibrational bands of Cu(dmpd)2 compared to bis(benzoylacetonato) copper (II), Cu(bzac)2 and bis(2,2,6,6-tetramethylheptane-3,5-dionato)copper(II), Cu(tmhd)2, by the mentioned theoretical and experimental techniques. All of the simulated and spectroscopic methods supported that the Cu-O bond strength of Cu(dmpd)2is closeto Cu(bzac)2 and more than that Cu(tmhd)2 complex. Comparing the experimental and theoretical vibrational wavenumbers indicates that the transform is the major configuration in the specimen, which agrees with reported the single crystallography results.

Functionalization of [60]Fullerene through photochemical reaction for fulleropyrrolidine nanovectors synthesis: Experimental and theoretical approaches

To develop novel carbon-based nanocarriers, we proposed grafting on the [60]Fullerene (C60) biologically active molecules. In this process, the formed derivatives described another approach to use photo-cycloaddition reactions for developing the third nanovector generation. As a result, the photoexcitation of C60 and azomethine ylide (AZMYtrp), with visible light, was considered as the most promising pathway to synthesize fulleropyrrolidine (FPL). After complexation with sodium cation (Na+), the error masses of FPL mono-, bis- and tris-adducts were remarkably decreased to -85.93 %, -53.99 % and -99.42 %, respectively. The formed FPL-Na+ complexes presented a significant capacity for trapping OH and OOH free radicals. In fact, their antiradical properties increased when Na+ was bonded with FPL-Na+ mono-adduct carbonyl oxygens. Comparing FPL bis-adducts regioisomers, under three different AZMYtrp forms, the neutral and anionic-neutral forms of FPL cis1 isomer were considered as the most reactive bis-nanocarriers with mole fractions of about 61 % and 46 %, respectively, in contrast to FPL-Na+, when the mixture was dominated by the anionic-neutral form of cis2 isomer with 50.34 %.

Isomerization of trans-3-methylglutaconic acid.

3‐Methylglutaconic (3MGC) aciduria is a common phenotypic feature of a growing number of inborn errors of metabolism. “Primary” 3MGC aciduria is caused by deficiencies in leucine pathway enzymes while “secondary” 3MGC aciduria results from inborn errors of metabolism that impact mitochondrial energy production. The metabolic precursor of 3MGC acid is trans‐3MGC CoA, an intermediate in the leucine catabolism pathway. Gas chromatography‐mass spectrometry (GC‐MS) analysis of commercially available trans‐3MGC acid yielded a mixture of cis and trans isomers while 1H‐NMR spectroscopy of trans‐3MGC acid at 25°C provided no evidence for the cis isomer. When trans‐3MGC acid was incubated under conditions used for sample derivatization prior to GC‐MS (but with no trimethylsilane added), 1H‐NMR spectroscopy provided evidence of trans to cis isomerization. Incubation of trans‐3MGC acid at 37°C resulted in time‐dependent isomerization to cis‐3MGC acid. Cis‐3MGC acid behaved in a similar manner except that, under identical incubation conditions, less isomerization occurred. In agreement with these experimental results, molecular modeling studies provided evidence that the energy minimized structure of cis‐3MGC acid is 4 kJ/mol more stable than that for trans‐3MGC acid. Once generated in vivo, trans‐3MGC acid is proposed to isomerize via a mechanism involving π electron delocalization with formation of a resonance structure that permits bond rotation. The data presented are consistent with the occurrence of both diastereomers in urine samples of subjects with 3MGC aciduria.

Triptycene-derived heterocalixarene: A new type of macrocycle-based stationary phases for gas chromatography

This work reports the investigation of a new triptycene-derived oxacalixarene (TDOC) as the stationary phase for gas chromatography (GC) with high-resolution performance for a wide range of analytes and isomers. The TDOC scaffold is composed of triptycene and 1,8-naphthyridine moieties, inherently differing from the conventional calixarenes in structures and properties. As a result, the TDOC column exhibited outstanding column efficiency of 5679 plates/m by n-dodecane at 120 °C. It showed advantageous performance for separations of the mixtures with various analytes and achieved high resolution of diverse isomers (skeletal, positional and cis-/trans-isomers) from apolar to polar nature. Moreover, the TDOC column exhibited high thermal stability up to 310 °C. To date, the TDOC-based materials have not been reported in chromatography. This work demonstrates the good potential of the triptycene-derived heterocalixarenes as a new class of stationary phases for chromatographic analyses.

Photoinduced Mechanical Motions of Pseudorotaxane Crystals Composed of Azobenzene and Ferrocenyl Groups on an Axle and a Crown Ether Ring.

This work describes the design and characterization of photoresponsive dynamic pseudorotaxane crystals composed of azobenzene and ferrocenyl groups in an ammonium cation axle component threaded through dibenzo[24]crown-8 ether rings. Pseudorotaxanes provide flexibility for cis and trans isomerization of azobenzene groups in a crystal state, enabling reversible bending motions under alternating 360 and 445 nm laser irradiation. For such bending motions, strained azobenzene structures were essential; these motifs were obtained by increasing the bulkiness of the substituents on the axle and ring molecules. In addition, the crystals showed photosalient effects, such as jumping motions, under 445 nm laser irradiation. These motions were assisted by the photoabsorption of the ferrocenyl group, which converted 445 nm laser light into heat. The maximum lifting weight accompanied by the photoinduced mechanical motion of a particular crystal was estimated to be 9600 times the crystal weight. These pseudorotaxane crystals exhibit promising features for applications in micro-nanometer-sized miniature mechanical devices.

Synthesis, crystal structure, DFT calculation and trans → cis isomerisation studies of bipyridyl ruthenium(II) complexes bearing 8-oxyquinolate azo ligands

Two stable Ru(II) bipyridyl complexes were synthesized with the deprotonated forms of the azo ligands of 8-hydroxyquinoline (hq) as analogues and they were chromatographically separated. The extended azo ligands coordinated as a bidentate ligand and chelates to ruthenium(II) through 8-quinolinolate moiety, leaving the azo part free from coordination. The general formula of the complexes are [Ru(bpy)2(q)]+. Here, q− is the deprotonated form of 5-phenylazo-8-hydroxyquinoline (Hq1) and 5-(2-naphthylazo)-8-hydroxyquinoline (Hq2). The complexes were verified by 1H NMR, ESI-mass, absorption-emission spectra, cyclic voltammetry and single-crystal X-ray structure determination. UV light-induced trans → cis isomerization and reverse isomerism i.e. cis → trans around -N=N- bond at room temperature were proposed from the UV-Vis spectral changes as well as the changing of the colour of the solution of the complexes. In aid of understanding the electronic charge distribution and charge-transfer properties, computational studies employing DFT and TDDFT method have been executed. Significant alteration in absorption spectra and colour change was observed for trans-cis photo-isomerization of the complexes upon UV light irradiation due to presence of free rotating azo groups

The Photoisomerization Pathway(s) of Push-Pull Phenylazoheteroarenes*.

Azoheteroarenes are the most recent derivatives targeted to further improve the properties of azo‐based photoswitches. Their light‐induced mechanism for trans–cis isomerization is assumed to be very similar to that of the parent azobenzene. As such, they inherited the controversy about the dominant isomerization pathway (rotation vs. inversion) depending on the excited state (nπ* vs. ππ*). Although the controversy seems settled in azobenzene, the extent to which the same conclusions apply to the more structurally diverse family of azoheteroarenes is unclear. Here, by means of non‐adiabatic molecular dynamics, the photoisomerization mechanism of three prototypical phenyl‐azoheteroarenes with increasing push–pull character is unraveled. The evolution of the rotational and inversion conical intersection energies, the preferred pathway, and the associated kinetics upon both nπ* and ππ* excitations can be linked directly with the push–pull substitution effects. Overall, the working conditions of this family of azo‐dyes is clarified and a possibility to exploit push–pull substituents to tune their photoisomerization mechanism is identified, with potential impact on their quantum yield.

Preparation of Photoresponsive Film via Electrodeposition Approach for Ready‐to‐Use Solar Thermal Fuel Device

AbstractAzobenzene and its derivatives are proposed as promising solar thermal fuel (STF) candidates due to the unique photoinduced trans–cis isomerization. However, the routinely processed azobenzene/inorganic–nonmetal nanocomposite‐based STF usually encounters the problems of close‐packed structure and the poor penetration of UV light, which need a solvent pretreatment charging process before STF application. Electrochemical deposition (ED) is widely used in the preparation of photoelectric functional devices because of its unique polymerization and deposition process. Here, an azobenzene‐based cross‐linking film is successfully prepared from a new functionalized azobenzene derivative, BCz‐BO‐Azo, by ED approach to develop a ready‐to‐use STF film without any pretreatments. The energy density of BCz‐BO‐Azo is 101 J g−1, and the energy storage half‐life of BCz‐BO‐Azo ED film is extended by 750% compared with that of pristine BCz‐BO‐Azo solid. The charged BCz‐BO‐Azo ED film also can release thermal energy to heat up itself quickly under a certain external stimulus. Due to the fast charging process, long energy storage half‐life, and quick stimulated release of the BCz‐BO‐Azo ED film, this kind of ready‐to‐use STF has distinct superiority in daily use, such as self‐defrosting glasses, building wall insulation, and solar energy transport.

Vitamin A aldehyde-taurine adduct and the visual cycle

Visual pigment consists of opsin covalently linked to the vitamin A-derived chromophore, 11-cis-retinaldehyde. Photon absorption causes the chromophore to isomerize from the 11-cis- to all-trans-retinal configuration. Continued light sensitivity necessitates the regeneration of 11-cis-retinal via a series of enzyme-catalyzed steps within the visual cycle. During this process, vitamin A aldehyde is shepherded within photoreceptors and retinal pigment epithelial cells to facilitate retinoid trafficking, to prevent nonspecific reactivity, and to conserve the 11-cis configuration. Here we show that redundancy in this system is provided by a protonated Schiff base adduct of retinaldehyde and taurine (A1-taurine, A1T) that forms reversibly by nonenzymatic reaction. A1T was present as 9-cis, 11-cis, 13-cis, and all-trans isomers, and the total levels were higher in neural retina than in retinal pigment epithelium (RPE). A1T was also more abundant under conditions in which 11-cis-retinaldehyde was higher; this included black versus albino mice, dark-adapted versus light-adapted mice, and mice carrying the Rpe65-Leu450 versus Rpe65-450Met variant. Taurine levels paralleled these differences in A1T. Moreover, A1T was substantially reduced in mice deficient in the Rpe65 isomerase and in mice deficient in cellular retinaldehyde-binding protein; in these models the production of 11-cis-retinal is compromised. A1T is an amphiphilic small molecule that may represent a mechanism for escorting retinaldehyde. The transient Schiff base conjugate that the primary amine of taurine forms with retinaldehyde would readily hydrolyze to release the retinoid and thus may embody a pool of 11-cis-retinal that can be marshalled in photoreceptor cells.

A systematic approach to methyl cinnamate photodynamics

ABSTRACT Methyl cinnamate (MC) is an ester within the cinnamate family. Recent time-resolved gas-phase studies have suggested that upon excitation to its first singlet ππ* (11ππ*) state, there is initial decay to the lowest lying singlet 1nπ* (11nπ*) state within 10 ps, en route to trans–cis isomerisation. In the present study, we have implemented time-resolved ion yield (TR-IY) and time-resolved photoelectron spectroscopy (TR-PES) experiments in the gas-phase to precisely determine the lifetime of the 11ππ* state. We found this lifetime to be ∼ 4.5 ps using both TR-IY and TR-PES. MC was also studied in a more complex cyclohexane solution environment, using transient electronic absorption spectroscopy. Along with complementary steady-state irradiation and 1H NMR studies, these studies demonstrate that trans–cis isomerisation is preserved in the more complex, cyclohexane solution environment.