UV/VIS spectral properties of novel natural products from Turkish lichens

Posokhov, Yevgen O.; Erten, Sinan; Koz, Ömer; Anıl, Hüseyın; Kirmizigul, Suheyla; İçli, Sıddık

doi:10.1155/s1110662x0500005x

Cited by 8 publications

(2 citation statements)

References 12 publications

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“…The ground-state UV/vis absorption spectra of 1 (thick line), NDI (thin solid line), and Pt(phen)Cl 2 (thin dashed line) are depicted in Figure . The absorption spectrum of NDI is dominated by a transition to the lowest excited singlet S 1 state of NDI ,− in the range 320−390 nm with the well-resolved vibronic structure. The spectrum of Pt(phen)Cl 2 contains an intense intraphenanthroline absorption at about 260 nm, and an MLCT absorption band at 395 nm.…”

Section: Resultsmentioning

confidence: 99%

Excited State Dynamics of a Pt^IIDiimine Complex bearing a Naphthalene-Diimide Electron Acceptor

Sazanovich¹,

Alamiry²,

Best³

et al. 2008

Inorg. Chem.

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A combination of picosecond time-resolved infrared spectroscopy, picosecond transient absorption spectroscopy, and nanosecond flash photolysis was used to elucidate the nature and dynamics of a manifold of the lowest excited states in Pt(phen-NDI)Cl 2 ( 1), where NDI = strongly electron accepting 1,4,5,8-naphthalene-diimide group. 1 is the first example of a Pt (II)-diimine-diimide dyad. UV/vis/IR spectroelectrochemistry and EPR studies of electrochemically generated anions confirmed that the lowest unoccupied molecular orbital (LUMO) in this system is localized on the NDI acceptor group. The lowest allowed electronic transition in Pt(phen-NDI)Cl 2 is charge-transfer-to-diimine of a largely Pt-->phen metal-to-ligand charge-transfer (MLCT) character. Excitation of 1 in the 355-395 nm range initiates a series of processes which involve excited states with the lifetimes of 0.9 ps ( (1)NDI*), 3 ps ( (3)MLCT), 19 ps (vibrational cooling of "hot" (3)NDI and of "hot" NDI ground state), and 520 mus ( (3)NDI). Excitation of 1 with 395 nm femtosecond laser pulses populates independently the (1)MLCT and the (1)NDI* excited states. A thermodynamically possible decay of the initially populated (1)MLCT to the charge-transfer-to-NDI excited state, [Pt (III)(phen-NDI (-*))Cl 2], is not observed. This finding could be explained by an ultrafast ISC of the (1)MLCT to the (3)MLCT state which lies about 0.4 eV lower in energy than [Pt (III)(phen-NDI (-*))Cl 2]. The predominant decay pathway of the (3)MLCT is a back electron transfer process with approximately 3 ps lifetime, which also causes partial population of the vibrationally hot ground state of the NDI fragment. The decay of the (1)NDI* state in 1 populates vibrationally hot ground state of the NDI, as well as vibrationally hot (3)NDI. The latter relaxes to form (3)NDI state, that is, [Pt(phen- (3)NDI)Cl 2]*, which possesses a remarkably long lifetime for a Pt (II) complex in fluid solution of 520 mus. The IR signature of this excited state includes the nu(CO) bands at 1607 and 1647 cm (-1), which are shifted considerably to lower energies if compared to their ground-state counterparts. The assignment of the vibrational bands is supported by the density-functional theory calculations in CH 2Cl 2. Pt(phen-NDI)Cl 2 acts as a modest photosensitizer of singlet oxygen.

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Section: Resultsmentioning

confidence: 99%

Excited State Dynamics of a Pt^IIDiimine Complex bearing a Naphthalene-Diimide Electron Acceptor

Sazanovich¹,

Alamiry²,

Best³

et al. 2008

Inorg. Chem.

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“…Many microbiological activity studies of some lichens explain the activities on gram (+) and gram (-) bacteria and fungi [13][14][15]. Two studies on Turkish lichens explain the isolation and structural determination of some natural products and their fluorescence emission properties, and some of them describe the volatile compounds of some lichens [16,17]. In the present study, the chemical composition of apolar phases of the above lichens was reported by a gas chromatography-mass spectrometry (GC-MS) combined system, and the results were examined in terms of EFAs and their importance for a healthy diet.…”

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confidence: 99%

Constituents of apolar extracts including essential fatty acids of some Turkish lichens

2007

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The number of known lichen species is about 18.000. Some of their metabolic products appear only in lichens, while others are also present in higher plants and fungi. Their secondary metabolites play a dominant role in their system [1,2]. Lichens have long been used for commercial purposes such as alcohol production and in the perfume, dye, and drug industries, and as food [3,4]. About 60 lichen species are present in different types of antimicrobial, anticancer, antiallergen, immunogical, and expectoral drugs [5][6][7][8][9]. Previous reports on many lichen species have been used to measure air pollution by detecting SO 2 and heavy and radioactive metals. The role of photoactive lichen substances in photosynthesis has been examined in environmental pollution [10,11]. Many scientists have been studying the carbohydrate composition of lichens. β-D-Glucans, which are linked to polyols, are also important in medicine because of their antitumor activities [5,12]. Many microbiological activity studies of some lichens explain the activities on gram (+) and gram (-) bacteria and fungi [13][14][15]. Two studies on Turkish lichens explain the isolation and structural determination of some natural products and their fluorescence emission properties, and some of them describe the volatile compounds of some lichens [16,17]. In the present study, the chemical composition of apolar phases of the above lichens was reported by a gas chromatography-mass spectrometry (GC-MS) combined system, and the results were examined in terms of EFAs and their importance for a healthy diet. In addition to this, volatile compounds were detected for the first time from E. prunastri and L. vulpina.The nineteen known apolar compounds of P. furfuracea, E. prunastri, and L. vulpina are given in Table 1. Besides these, 2-hydroxy-4-methoxy-3,6-dimethylbenzoic acid was isolated for the first time from P. furfuracea. In Table 1, the given compounds are known except cis-4b, 5,9,10-tetrahydro-8-methoxy-5-methylindenol [1,2-b] indole from E. prunastri. This compound was detected for the first time from this lichen species. Detected compounds and their percentages for L. vulpina are given in Table 1. The compound 1,2-benzenedicarboxylic acid bis (2-ethylhexyl) ester [bis(2-ethylhexyl) phthalate] was found for the first time from this material. The GC-MS results showed that the linoleic acid (LA) and α-linolenic acid (ALA) percentages were much higher than for other compounds in these studied lichen species. The percentages of them are also much greater than for higher plants.It is known that some kinds of polyunsaturated fatty acids (PUFA) cannot be synthesized by mammalian cells, and therefore they have to be provided by diet [18]. The intakes of EFAs (LA and ALA) must balance each other. The desirable intake quantities of these two chemicals have been reported as 10.04 and 1.55 grams a day in terms of LA and ALA amounts. The recommended required daily minimum intake ratio of LA to ALA leading to a substantial health change is about 6:1 [18]. The mediterr...

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Relativistic two-component density functional study of ethyl 2-(2-Iodobenzylidenehydrazinyl)thiazole-4-carboxylate

Wasif Baig,

Mehmood,

Akhtar

2024

Computational and Theoretical Chemistry

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UV/VIS spectral properties of novel natural products from Turkish lichens

Cited by 8 publications

References 12 publications

Excited State Dynamics of a Pt^IIDiimine Complex bearing a Naphthalene-Diimide Electron Acceptor

Excited State Dynamics of a Pt^IIDiimine Complex bearing a Naphthalene-Diimide Electron Acceptor

Constituents of apolar extracts including essential fatty acids of some Turkish lichens

Relativistic two-component density functional study of ethyl 2-(2-Iodobenzylidenehydrazinyl)thiazole-4-carboxylate

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UV/VIS spectral properties of novel natural products from Turkish lichens

Cited by 8 publications

References 12 publications

Excited State Dynamics of a PtIIDiimine Complex bearing a Naphthalene-Diimide Electron Acceptor

Excited State Dynamics of a PtIIDiimine Complex bearing a Naphthalene-Diimide Electron Acceptor

Constituents of apolar extracts including essential fatty acids of some Turkish lichens

Relativistic two-component density functional study of ethyl 2-(2-Iodobenzylidenehydrazinyl)thiazole-4-carboxylate

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Excited State Dynamics of a Pt^IIDiimine Complex bearing a Naphthalene-Diimide Electron Acceptor

Excited State Dynamics of a Pt^IIDiimine Complex bearing a Naphthalene-Diimide Electron Acceptor