Pyridine Solution Research Articles

A Macrocyclic Bistriazene and its Complexes with Divalent Metal Ions

AbstractThe diazotisation of 2,2′‐diaminotolane with one equivalent of HNO2 yields the macrocyclic bis(tolanetriazene) (tolaneN3H)2 in moderate yield. As shown by the crystal structure determination, the molecule is essentially planar. After deprotonation, the central cavity is suitable for complexation of transition metal ions. In pyridine solution, the anion (tolaneN3)22– is formed, which reacts with the acetates of Co2+ and Ni2+ to the dark red coloured complexes [M((tolaneN3)2)(py)2]. The metal ions are located in the centre of the macrocycles, coordinated by four N atoms of the two triazenide groups. Two pyridine ligands occupy the axial positions, giving the central atoms a distorted octahedral coordination environment. In the temperature range between 30 and 300 K, both complexes show the expected magnetic properties of magnetically isolated ions with nearly fulfilled Curie behaviour and μeff = 3.40 for NiII and 5.19 for CoII, which is in the high spin state.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

The Influence of N-Heterocyclic Carbenes (NHC) on the Reactivity of [Ru(NHC)4H]+With H2, N2, CO and O2

The five-coordinate ruthenium N-heterocyclic carbene (NHC) hydrido complexes [Ru(IiPr(2)Me(2))(4)H][BAr(F) (4)] (1; IiPr(2)Me(2)=1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene; Ar(F)=3,5-(CF(3))(2)C(6)H(3)), [Ru(IEt(2)Me(2))(4)H][BAr(F) (4)] (2; IEt(2)Me(2)=1,3-diethyl-4,5-dimethylimidazol-2-ylidene) and [Ru(IMe(4))(4)H][BAr(F) (4)] (3; IMe(4)=1,3,4,5-tetramethylimidazol-2-ylidene) have been synthesised following reaction of [Ru(PPh(3))(3)HCl] with 4-8 equivalents of the free carbenes at ambient temperature. Complexes 1-3 have been structurally characterised and show square pyramidal geometries with apical hydride ligands. In both dichloromethane or pyridine solution, 1 and 2 display very low frequency hydride signals at about delta -41. The tetramethyl carbene complex 3 exhibits a similar chemical shift in toluene, but shows a higher frequency signal in acetonitrile arising from the solvent adduct [Ru(IMe(4))(4)(MeCN)H][BAr(F) (4)], 4. The reactivity of 1-3 towards H(2) and N(2) depends on the size of the N-substituent of the NHC ligand. Thus, 1 is unreactive towards both gases, 2 reacts with both H(2) and N(2) only at low temperature and incompletely, while 3 affords [Ru(IMe(4))(4)(eta(2)-H(2))H][BAr(F) (4)] (7) and [Ru(IMe(4))(4)(N(2))H][BAr(F) (4)] (8) in quantitative yield at room temperature. CO shows no selectivity, reacting with 1-3 to give [Ru(NHC)(4)(CO)H][BAr(F) (4)] (9-11). Addition of O(2) to solutions of 2 and 3 leads to rapid oxidation, from which the Ru(III) species [Ru(NHC)(4)(OH)(2)][BAr(F) (4)] and the Ru(IV) oxo chlorido complex [Ru(IEt(2)Me(2))(4)(O)Cl][BAr(F) (4)] were isolated. DFT calculations reproduce the greater ability of 3 to bind small molecules and show relative binding strengths that follow the trend CO >> O(2) > N(2) > H(2).

Electrochemical, spectroelectrochemical and ESR spectroscopic characterization of 2,3- and 3,4-cobalt tetrapyridoporphyrazine isomers in non-aqueous media

Two cobalt porphyrazines, 2,3-tetrapyridoporphyrazine and 3,4-tetrapyridoporphyrazine, were examined in N,N-dimethylformamide, dimethyl sulfoxide and pyridine solutions as to their electrochemical, spectroelectrochemical and ESR spectroscopic properties. These results were compared with those of the unsubstituted cobalt phthalocyanine. At high concentrations, aggregation was observed for each investigated compound in the three solvents. The intensity of ESR signals of each derivative depends upon the extent of aggregation in its solution. The g values shift towards high field with an increase in the strength of the axial ligand and the number of axial ligands on the cobalt center. Both tetrapyridoporphyrazine complexes undergo one oxidation and three reductions in N,N-dimethylformamide, dimethyl sulfoxide or pyridine solution. Thin-layer UV-visible spectroelectrochemical results confirmed that the first oxidation and first reduction of both compounds are metal-centered while the second and third reductions are ring-centered. An overall electron transfer mechanism for both porphyrazine derivatives is proposed.

Gibbs energy of cooperative hydrogen‐bonding interactions in aqueous solutions of amines and pyridines

AbstractA method to determine the Gibbs energy of specific (hydrogen bonding) interactions of a solute with water is proposed. The energies of hydrogen bonding in bulk water are very difficult to determine by any method. The Gibbs energy of hydration of substances forming hydrogen bonds with water is considered as the sum of contributions due to non‐specific interactions, the hydrophobic effect, and specific interactions. The first two terms were found to be rather accurately described by empirical equations. The Gibbs energies of hydrogen bonding of aliphatic amines and pyridines in bulk water are determined, and the results are compared with the energies of their complexes with one molecule of water. The cooperativity of hydrogen bonding is proved in aqueous solutions of amines and pyridines. To use our equations, experimental values of the Gibbs energies of solvation in 'standard' solvents need to be known. The Gibbs energies of solvation of ten amines and pyridines in dimethyl sulfoxide are determined experimentally using chromatographic head space analysis. The tendencies observed for the series of amines and pyridines are in agreement with other studies. Copyright © 2009 John Wiley & Sons, Ltd.

Crystallinity and properties of C60 nanotubes improved by annealing and alcohol-soaking

Well-uniformed C60 nanotubes were grown at -20 °C with irradiation of red light using C60-saturated pyridine solution and isopropyl alcohol by a liquid-liquid interfacial precipitation method without ultrasonic pulverization. We attempted to improve their crystallinity by two post-treatments; thermal annealing and alcohol-soaking. The crystallinity of as-grown and dried C60 nanotubes, which was poor due to the evaporation of solvent molecules from crystals in the drying process, was improved by annealing around 220 °C for 5 hours in vacuum. Dramatic improvement of crystallinity of as-grown samples was achieved by soaking into methanol and then drying in air. Raman, infrared and X-ray diffraction results suggest that the methanol-soaked samples exhibit a solvated tetragonal structure. The crystallinity improved by methanol-soaking did not degrade after removal of methanol molecules from samples by thermal annealing. Photo-polymerization of the structurally-improved C60 nanotubes was examined to investigate an effect of crystallinity on the polymerization kinetics.

基于CuPcF16的近红外电致发光器件

We demonstrate the near-infrared (NIR) organic light-emitting devices (OLEDs) based on copper hexadecafluorophthalocyanine (CuPcF16 doped into 2,2,2-(1,3,5-benzenetriyl)tris-[1-phenyl-1H-benzimidazole] (TPBI). The device structure is ITO/ NPB/ TPBI:CuPcF16/BCP/Alq3/Al. Room-temperature electroluminescence is observed at about 1106 nm due to transitions from the first excited triplet state to the ground state (T1-S0) of CuPcF16. The result indicates that Forster and Dexter energy transfers play a minor role in these devices, while the direct charge trapping is the dominant mechanism. The absorption spectra of CuPcF16 solution in pyridine and vacuum sublimed films on quartz have also been investigated.

Phase Structure and Mechanical Property of Blends of Organosolv Lignin Alkyl Esters with Poly(ε-caprolactone)

Organosolv lignin (OSL) alkyl esters (carbon number n, 2–5) were synthesized by homogeneous reaction with different acyl anhydrides/4-dimethylamino pyridine in pyridine solution. Miscibility of the esterified OSL with poly(ε-caprolactone) (PCL) was investigated through DSC, morphological observation, and spectroscopy. DSC revealed a composition-dependent shift in Tg for blends of OSL esters (n = 3–5) with PCL; thus these three systems can be regarded as miscible on a Tg-detection scale. AFM indicated that no remarkable phase separation occurred in these blends. In observations of crystallization behavior of the PCL component, the OSL derivatives of n = 4 and 5, the alkyl ester substituents of which make a higher similarity in chemical structure with a repeating unit of PCL, exhibited a higher level of miscibility with the aliphatic polyester, compared to the other OSL derivative of n = 3. Thermal-molded blend sheets of OSL esters of n = 3–5 with PCL attained ≥500% of elongation at rupture at 20 °C even when the blends contained 50 wt% of the respective esterified lignin components, reflecting the good miscibility of these OSL esters with PCL.

Synthesis and crystal structure of pentavalent uranyl complexes. The remarkable stability of UO2X (X = I, SO3CF3) in non-aqueous solutions

The reaction of [UO(2)I(2)(THF)3] with KC(5)R(5) (R = H, Me) or K(2)C(8)H(8) in pyridine gave crystals of [{UO(2)(py)(5)}{KI2(py)2}]. (1), which were desolvated under vacuum into pulverulent [UO(2)(py)2.2KI2] (2).Similar reactions with [UO2(OTf)2] afforded [UO2(py)2.3K(OTf)2] (3) as a powder and crystals of [{UO(2)(py)(5)}2{K(3)(OTf)(5)}. py]. (4.py), which were also obtained together with crystals of [{UO2(py)5}2{K(OTf)2(py)2}][OTf] py (5. py) by treating [UO2(OTf)2] with KC(4)Me(4)P. Crystals of 6. py, the thallium analogue of 5. py, were isolated from the reaction of [UO2(OTf)2] and TlC5H5. Treatment of[UO2I2(THF)3] with LiCH2SiMe3 in pyridine afforded crystals of [{UO(2)(py)5}{LiI(py)2}][I] (7) while[UO(2)(OTf)2] reacted with the alkyllithium reagent in acetonitrile to give crystals of [{UO2(py)5}{Li2(OTf)3}]. (8) in pyridine. The crystal structures of 1, 4. py, 5. py, 6. py, 7 and 8 revealed the presence of U=O-->M interactions (M = Li, K, Tl), and the rich diversity of these structures, from dinuclear (7) to 3D polymeric (4), is related to the distinct coordination numbers of the M+ ion and ligation modes of the bridging iodide and triflate ligands as well as the presence of U=O-->M interactions. The mononuclear complexes [UO2(OTf)(THF)n] (9) and [UO2(OTf)(Et2O)0.5] (10) were respectively obtained by reaction of [UO2(OTf)2] with KC5R5 in THF or LiCH2SiMe3 in Et2O, and were transformed into [UO(2)(OTf)(py)2] (11) in pyridine. Treatment of [UO(2)I(2)(THF)3] with TlC5H5 inpyridine afforded crystals of [UO2(py)5][I]. py (12. py) which were desolvated under vacuum into the powder of [UO(2)I(py)2.5] (14). The same reaction in THF gave [UO2I(THF)2.7] (13) in powder form.Crystals of [UO(2)(CyMe4BTBP)(py)][OTf]. 1.5py (15. 1.5py) and the powder of [UO2I(CyMe4BTBP)](16) were obtained by treating [UO(2)(CyMeBTBP)X2] (X= OTf, I) with KC5Me5 or TlC5H5,respectively. The uranyl(V) chloride and nitrate compounds [UO(2)Cl(py)3] (17) and [UO2(NO3)(py)3] (18)were prepared by reaction of the uranyl(VI) precursors with TlC5H5 in pyridine; complex 18 was also obtained by treating 13 with TlNO3. Crystals of the neutral mononuclear complex [UO(2)(OTf)(py)4] (19)were isolated from reaction of [UO(2)(OTf)2] with Me3SiC5H5 in acetonitrile. Similar reaction with [UO(2)Cl(2)(THF)2]2 in pyridine gave crystals of [UO(2)Cl(2)(py)3]. The crystal structures of 12 py, 15. 1.5py and 19 were determined; the structure of 15 was compared with that of the uranyl(VI) counterpart. All the uranyl(V) compounds are remarkably stable in pyridine solution; the IR absorption at 816 cm-1 is attributed to the v (asym)(U=O) of the ubiquitous [UO(2)(py)(5)]+ species.

Structural Prediction for a Chiral Copper(II) Complex in Solution by Circular Dichroism Spectra

The molecular structures in solutions were predicted for a chiral copper(II) complex [Cu(R-mben)2]2+ [R-mben = N-(methylbenzyl)ethylenediamine] based on the circular dichroism (CD) spectra in an acetonitrile solution and a pyridine solution. Each CD spectrum was analyzed to obtain the spectral components, and the coordination geometry around the copper(II) ion was estimated to be square-pyramidal on the basis of the observed spectral components. The structures of twelve probable conformers were optimized by DFT computation, and the CD spectrum was predicted for each structure by the TD-DFT method. Then, comparing the observed CD data with the predicted CD data, the structures in solutions were estimated.

Microwave‐assisted synthesis and characterization of heterocyclic, and optically active poly(amide‐imide)s incorporating L‐amino acids

AbstractN,N′‐Pyromelliticdiimido‐di‐L‐alanine (1), N,N′‐pyromelliticdiimido‐di‐L‐phenylalanine (2), and N,N′‐pyromelliticdiimido‐di‐L‐leucine (3) were prepared from the reaction of pyromellitic dianhydride with corresponding L‐amino acids in a mixture of glacial acetic acid and pyridine solution (3/2 ratio) under refluxing conditions. The microwave‐assisted polycondensation of the corresponding diimide‐diacyl chloride monomers (5–7) with 4‐phenyl‐2,6‐bis(4‐aminophenyl) pyridine (10) or 4‐(p‐methylthiophenyl)‐2,6‐bis(4‐aminophenyl) pyridine (12) were carried out in a laboratory microwave oven. The resulting poly(amide‐imide)s were obtained in quantitative yields, and they showed admirable inherent viscosities (0.12–0.55 dlg−1), were soluble in polar aprotic solvents, showed good thermal stability and high optical purity. The synthetic compounds were characterized by IR, MS, 1H NMR, and 13C NMR spectroscopy, elemental analysis, and specific rotation. Copyright © 2008 John Wiley & Sons, Ltd.

Facile Syntheses of Some Thieno[2,3-d] Pyrimidine Derivatives

In one-pot synthesis 2-arylidene-5,6,7,8-tetrahydrothiazolo[3,2-a] cyclopenteno-thieno[2,3-d] pyrimidine-3,5-diones (3) were prepared via the reaction of a ternary mixture of 2-thioxo-1,3,4,5,6,7-hexahydr cyclopentinothieno [2,3-d]-4-one (2), chloroacetic acid and a proper aldehyde. Compound 2 reacted with 3-chloropent-2, 4-dione in ethanolic potassium hydroxide yielding the S-acetyl acetone derivative 5f . The latter compound reacted with hydrazine hydrate and phenyl hydrazine yielded the 2-pyrazolthio derivative 10a, b. Compound 5f also underwent cyclization on heating with acetic acid—pyridine solution to give 11. The 2-methylthio derivative 5a, when treated with hydrogen peroxide gave the corresponding oxidized product 9.

Nano-textured metallic surfaces for optical sensing and detection applications

This work describes fabrication of three-dimensionally nano-textured silicon surface structures metalized by thin gold films, and their application for optical sensing and detection of solute molecules utilizing surface-enhanced Raman scattering (SERS) effect. Two types of sensitive surfaces were prepared by different techniques. The first of them was a checkerboard pattern of 3D nanoblocks defined in compact areas on the surface of a silicon wafer using highly accurate electron-beam lithography (EBL) technique, and fabricated by dry reactive-ion etching (RIE) technique with subsequent metalization of the surface by gold sputtering. The second type of sensitive surface consisted of a square array of nano-apertures, defined on a large area of the silicon surface by a less accurate but simpler ultraviolet holographic lithography, and subsequently fabricated in a sequence of dry and wet etching as well as gold sputtering steps. The fabricated structures were found to exhibit significant near-field enhancement, as evidenced by strong SERS signal from the sensors immersed in aqueous pyridine solutions with concentrations as low as 10 −9 M due to the presence of well-defined 3D periodic texture of the structure.

A Stair‐Shaped Molecular Silver(0) Chain

A Stair‐Shaped Molecular Silver(0) Chain

Catena-Poly[[[aquatripyridinecobalt(II)]-μ-5-amino-2,4,6-triiodoisophthalato-κ2O1:O3] pyridine solvate

The reaction of cobalt(II) nitrate with 5-amino-2,4,6-tri­iodo­isophthalic acid (ATPA) in pyridine solution leads to the formation of the title compound, {[Co(C8H2I3NO4)(C5H5N)3(H2O)]·C5H5N}n. The Co2+ ion is six-coordinated by three N atoms, one water O atom and two O atoms from two ATPA ligands to form a distorted octa­hedral geometry. The two carboxyl­ate groups of ATPA act as bridging ligands connecting the CoII metal centers to form one-dimensional zigzag chains along the c axis, with Co—O distances in the range 2.104 (4)–2.135 (4) Å. The average Co—N distance is 2.171 Å. A classical O—H⋯N hydrogen bond is formed by the coordinating water mol­ecule and the pyridine solvent mol­ecule. The structure was refined from a racemically twinned crystal with a twin ratio of approximately 8:1.

Relationship Among the Raoult Law, Zdanovskii−Stokes−Robinson Rule, and Two Extended Zdanovskii−Stokes−Robinson Rules of Wang

In this paper, the Raoult law (C. R. Acad. Sci. Ser. C 1887, 104, 1430), the Zdanovskii−Stokes−Robinson (ZSR) rule (Trudy Solyanoi Laboratorii Akad. Nauk SSSR 1936, No. 6, 5; J. Phys. Chem. 1966, 70, 2126), and two extended ZSR rules of Wang (Acta Metall. Sinica 1980, 16, 195; Ber. Bunsen-Ges. Phys. Chem. 1998, 102, 1045) are presented in a unified way. Similar to the Raoult law, which was first noted empirically in pyridine solutions, the ZSR rule for isopiestic mixed electrolyte and nonelectrolyte aqueous solutions can be extended to every kind of liquid and solid solutions such as organic mixtures, aqueous and nonaqueous electrolyte and nonelectrolyte solutions, liquid and solid alloys, molten salt mixtures, slags, and nonstoichiometric solid solutions, resulting in two extended ZSR rules of Wang. Although the solutions obeying the Raoult law (or the related classically ideal solution model) are very few as compared with the classically nonideal solutions, one classically ideal solution {B+C+...+Z} may...

HIGH YIELD PREPARATION OF FULLERENE NANOWHISKERS AND NANOTUBES BY THE SOLUTION ROUTE

The effect of ultraviolet, visible and near-infrared irradiation on the yield and morphology of single crystalline C 60 fullerene nanowhiskers (FNWs) and nanotubes (FNTs) was investigated in an effort to produce large-scale quantities of FNWs and FNTs. These fullerene nanomaterials were synthesized by the liquid–liquid interfacial precipitation method using pyridine and isopropyl alcohol (IPA) as solvents. The C 60–pyridine solution was illuminated using different wavelengths for 24 h at ambient pressure and temperature before addition of IPA. High yields (30–38 mg/L) were obtained upon irradiation using wavelengths in the ultraviolet region in accordance with the increased photoabsorption signal of solid C 60 and C 60 dissolved in pyridine acquired by a UV-VIS-NIR spectrophotometer. However, elevated yields (21–27 mg/L) were also obtained in the 600–800 nm regions, where C 60 absorption is particularly weak. Such an enhanced yield of FNTs and FNWs is probably related to the reported rise in transient absorption of the triplet excited state of C 60 in the 740 nm region formed by the decay of the photoexcited singlet C 60 through intersystem crossing. The formation of photopolymerized fullerene nanofibers was also observed by Raman spectroscopy, it is attributed to ultraviolet and visible light irradiation. SEM and TEM observations suggest that preparation of FNWs and FNTs by irradiation using different wavelengths of light does not produce apparent morphological transformations on the surface of these fullerene materials.

Synthesis of Organo-soluble Tetrapyrazinoporphyrazines and Their Visible Spectra Properties

There were many researches about phthalocyanines for various applications such as chemical sensor, catalyst, etc. The unsubstituted metallophthalocyanines have intense colors but are generally insoluble in organic solvents or water, thereby limiting their use to just a few fields. It is well known that the insolubility of metal phthalocyanine derivatives results from their molecular stacking, which gives rise to strong intermolecular interactions between the macrocycles in the phthalocyanine molecules. There are, however, two methods of achieving solubility in almost all solvents. The first involves the use of a trior tetravalent transition metal as the core of the macrocycle, with the coordination compound having an axial ligand at the central metal. The second method involves the introduction of various peripheral substituents on the macrocycle. This minimizes the formation of aggregates, thereby improving the solubility. We have been studied the syntheses of functional dye materials based on 2,3-dicyanopyrazine chromophores, and correlated their physical properties with structures. In this paper, we designed and synthesized metal and metal-free tetrapyrazinoporphyrazines derived from 2,3-dicyano-5-(4tert-butylphenyl)-6-alkyl pyrazines derivatives for increasing solubility. Treatment of these 4-(tert-butyl)alkyl phenone derivatives with one equivalent of bromine in chloroform at room temperature gave α-brominated 4-(tert-butyl)alkyl phenone derivatives. α-Acetoxylated 4-(tert-butyl)alkyl phenone (obtained by the treatment of the α-brominated ketone with an excess of anhydrous potassium acetate in acetone) was reacted with 10% methanolic NaOH under reflux conditions to produce the corresponding compounds (2). The α-diketones (3) were obtained by the oxidation of α-hydroxyketone with copper sulfate in aqueous pyridine solution. Tetrapyrazinoporphyrazine precursors (4) were synthesized from α-diketones and diaminomaleonitrile, in the presence of a catalytic amount of p-toluenesulfonic acid in methanol. The final tetrapyrazinoporphyrazine magnesium complexes (5) were successfully synthesized using excess magnesium butoxide in n-butanol under reflux conditions. These magnesium complexes were easily demetalated. This was done by stirring them in excess p-toluenesulfonic acid, in THF, at room temperature, for 30 min, to produce 6 (in a yield range of 44-50%). The reaction route is summarized

Catena-Poly[[dipyridinemercury(II)]-μ-5-amino-2,4,6-triiodoisophthalato

The reaction of mercury(II) chloride with 5-amino-2,4,6-triiodo­isophthalic acid in pyridine solution leads to the formation of the title compound, [Hg(C8H2I3NO4)(C5H5N)2]n. The structure contains a four-coordinate Hg2+ ion in a distorted tetra­hedral geometry, which lies on a crystallographic twofold axis. The Hg2+ ion is bonded to two N atoms from two pyridine ligands and two carboxylate O atoms from two 5-amino-2,4,6-triiodo­isophthalate anions. The two carboxyl­ate groups of individual 5-amino-2,4,6-triiodo­isophthalate anions act as a bridge to the Hg centers. This anion also resides on a twofold axis, which passes through the amino N and the trans standing I atoms. The Hg—O distance is 2.337 (6) and the Hg—N distance is 2.244 (8) Å.

Fabrication of Calcite Aggregates and Aragonite Rods in a Water/Pyridine Solution

Polymorphs of calcium carbonate (CaCO3) have been easily synthesized in a water/pyridine mixed solvent system under mild conditions without using any other organic additives. The phase transition from pure aragonite to almost pure vaterite, and then to pure calcite, can be nicely captured by the choice of a suitable water to pyridine ratio. The formation mechanisms of calcium carbonate crystals have been proposed. A novel morphology of calcite, wire-like shaped, was found in pure pyridine solvent. A self-assembly process for the formation of wire-like calcite in pure pyridine solution has been proposed. The effect of experimental time on morphology of calcite is investigated in pure pyridine solvent. The results obtained proved that such reaction media could give an alternative and versatile tool for controlling both the structure and the polymorphism of inorganic materials.

Resonance Hyper-Raman Spectra of Zinc Phthalocyanine

Hyper-Raman spectra were obtained for zinc phthalocyanine in a dilute pyridine solution at excitation wavelengths that are two-photon resonant with the one-photon-allowed B band (360-380 nm) as well as with the two-photon absorption near 440 nm reported by Drobizhev et al. ( J. Chem. Phys. 2006, 124, 224701 ). In both regions, the hyper-Raman spectra were very different from the linear resonance Raman spectra at the corresponding excitation frequencies. While the resonance Raman spectra show only g symmetry modes, almost all of the hyper-Raman frequencies can be assigned as fundamentals of E u symmetry that also are observed in the infrared absorption spectrum or E u symmetry combination bands. These results contrast sharply with previous observations of highly noncentrosymmetric push-pull conjugated molecules and are consistent with a structure for phthalocyanine in solution that is centrosymmetric or nearly so. The hyper-Raman spectra show different intensity patterns in the two excitation regions, consistent with different Franck-Condon and/or vibronic coupling matrix elements for the different resonant states.