The Predictive Power of the Annellation Theory: The Case of the

Article pubs.acs.org/JPCA

The Predictive Power of the Annellation Theory: The Case of the C26H16 Cata-Condensed Benzenoid Polycyclic Aromatic Hydrocarbons Jorge O. Oña-Ruales*,† and Yosadara Ruiz-Morales‡ †

National Institute of Standards and Technology, NIST, Gaithersburg, Maryland 20899, United States Instituto Mexicano del Petróleo, Eje Central Lázaro Cárdenas Norte 152, Mexico City 07730, Mexico

J. Phys. Chem. A 2015.119:10451-10461. Downloaded from pubs.acs.org by UNIV OF LOUISIANA AT LAFAYETTE on 10/30/18. For personal use only.

‡

S Supporting Information *

ABSTRACT: The Annellation Theory was applied to establish the locations of maximum absorbance for the p and β bands in the UV−vis spectra of eight benzenoid cata-condensed polycyclic aromatic hydrocarbons (PAHs) with molecular formula C26H16 and no available syntheses procedures. In this group of eight isomers, there are seven compounds with potential carcinogenic properties due to geometrical constraints. In addition, crude oil and asphaltene absorption spectra exhibit similar properties, and the PAHs in heavier crude oils and asphaltenes are known to be the source of the color of heavy oils. Therefore, understanding the electronic bands of PAHs is becoming increasingly important. The methodology was validated using information for the remaining 29 isomers with available UV−vis spectra. The results satisfactorily agree with the results from semiempirical calculations made using the ZINDO/S approach. The locations of maximum absorbance for the p and β bands in the UV−vis spectra of the eight C26H16 cata-condensed isomers dibenzo[c,m]tetraphene, naphtho[1,2-c]chrysene, dibenzo[c,f ]tetraphene, benzo[f ]picene, naphtho[2,1-a]tetraphene, naphtho[2,1-c]tetraphene, dibenzo[c,l]chrysene, and naphtho[1,2-a]tetraphene were established for the first time. constrained geometry.5 Thus, the link between the nonplanarity of PAHs and their evidenced biological behavior suggests that not only compound XVII but also the other 20 constrained C26H16 PAHs may possibly constitute compounds with potential harmful biological activity. In spite of this fact, only 13 structures (XVII, XVIII, XX, XXI, XXII, XXIII, XXIV, XXV, XXVI, XXXIII, XXXIV, XXXV, and XXXVII) in the group of 21 C26H16 cata-condensed PAHs with geometrical constraint have reported synthesis procedures (ref 2 reports the syntheses of XVIII, XX, and XXXVII; ref 5 reports the synthesis of XVII; ref 6 reports the syntheses of XXI and XXV; ref 7 reports the synthesis of XXII; ref 8 reports the syntheses of XXIII and XXXIII; ref 9 reports the syntheses of XXIV, XXVI, and XXXIV; and ref 10 reports the synthesis of XXXV) and one structure (XIX) has an unreported synthesis procedure from W. Schmidt, Institut fur PAH-Forschung, Greifenberg, Germany. Consequently, there are still seven (XXVII, XXVIII, XXIX, XXX, XXXI, XXXII, and XXXVI) compounds with potential detrimental properties that have not yet been synthesized. Hence, the need exists for establishing experimental or theoretical procedures that lead to the character-

1. INTRODUCTION The benzenoid polycyclic aromatic hydrocarbons (PAHs) with cata-condensed configuration (also known as ortho-fused PAHs in IUPAC nomenclature), C(10+4x)H(8+2x) (where x = 1··· ∞), are linear, angular, and/or multibranched molecules formed by aromatic carbon atoms situated in one or a maximum of two molecular constitutive rings. The C26H16 group composed of 37 members, as it is presented in Figure 1,1 is among the most important groups in the cata-condensed class due to its combination of relatively low molecular mass structures (328 Da), low number of isomers (37), and an elevated percent (57%) of structures with steric hindrance regions, e.g., cove, fjord, and helical regions. Specifically, out of the 37 C26H16 catacondensed PAHs, 21 structures (Groups 3, 4, and 5 in Figure 1) are geometrically constrained, i.e., nonplanar. The 21 nonplanar structures are distributed in the following arrangement: 16 structures (Group 3) contain 1 or 2 cove regions and 0, 1, or 2 bay regions; 4 structures (Group 4) contain 1 fjord region and 0, 1, or 2 bay regions; and 1 structure (Group 5) contains one helical region. Comprehensive analyses have been performed about the influence of the geometric constraints on the biological activity of PAHs, e.g., carcinogenic potential, and conclusive relationships that demonstrate the connection of the nonplanar geometry with the carcinogenicity have been achieved.4,5 For example, compound XVII, presents a carcinogenic behavior that has been associated with its © 2015 American Chemical Society

Received: August 7, 2015 Revised: September 29, 2015 Published: September 30, 2015 10451

DOI: 10.1021/acs.jpca.5b07681 J. Phys. Chem. A 2015, 119, 10451−10461

Article

The Journal of Physical Chemistry A

Figure 1. C26H16 cata-condensed benzenoid PAHs classified according to the absence or presence of bay, cove, fjord, and helical regions. Group 1: Absence of bay, cove, fjord, or helical regions; Group 2: Presence of only bay regions; Group 3: Presence of 1 or 2 cove regions and 0, 1, or 2 bay regions; Group 4: Presence of 1 fjord region and 0, 1, or 2 bay regions; and Group 5: Presence of 1 helical region. The locations, number, and migrating behavior of the sextets in the PAHs I, XIX, XXV, XXXII, XXXVI, and XXXVII have been achieved by means of the information provided in ref 2. The locations, number, and migrating behavior of the sextets in the PAHs II, III, IV, V, VI, VII, VIII, IX, X, XI, XII, XIII, XIV, XV, XVI, XVII, XVIII, XX, XXI, XXII, XXIII, XIV, XXVI, XXVII, XXVIII, XXIX, XXX, XXXI, XXXIII, XXXIV, and XXXV have been achieved by means of the Extended Y-rule method.3 The structures in black denote the compounds with known UV−vis spectra, and the structures in red denote the compounds with unknown UV−vis spectra. The complete list of names for the PAH structures is included in the Supporting Information section (Figure S1). The black lines connecting rings denote the movement of the aromatic sextets.

transition from the highest occupied molecular orbital (HOMO) to the second lowest unoccupied orbital; second, the p bands located at intermediate wavelengths indicate a transition from the HOMO to the lowest unoccupied molecular orbital (LUMO); and third, the α bands generally located at high wavelengths indicate a transition from the second highest occupied molecular orbital to the LUMO. Based on this classification, the UV−vis spectra of cata-condensed PAHs are characterized by the following unique features that differentiate them from the UV−vis spectra of peri-condensed PAHs:2 1. The absorbance intensity average ratio of the β bands

ization of these seven nonplanar C26H16 cata-condensed PAHs with prospective unfavorable behavior. The UV−vis spectrum is a fingerprint that characterizes each PAH molecule. As illustrated in Figure 2, the UV−vis spectrum of pyrene (XXXVIII) shows three types of spectral bands:11 First, the β bands located at lower wavelengths indicate a

intensity β

versus the p bands ( intensity p = 6) is 3 times larger than that of the analogous absorbance intensity average ratio intensity β

of peri-condensed PAHs ( intensity p = 2 ); and 2. The presence of UV−vis spectral patterns with bundles of absorption bands that are not well-defined as illustrated in Figure 3 for PAHs XXXIX, XVII, and XL, in opposition to the UV−vis spectral patterns with regularly distributed and distinct absorption bands for peri-condensed PAHs, as illustrated in Figure 3 for PAHs XXXVIII, XLI, and XLII.

Figure 2. UV−vis spectrum of XXXVIII (pyrene). The symbols β, ρ, and α were given by Clar2 to characterize the UV−vis spectral bands of PAHs. 10452


Article


Figure 3. UV−vis spectra of the cata-condensed PAHs XXXIX, XVII, and XL, and the UV−vis spectra of the peri-condensed PAHs XXXVIII, XLI, and XLII. Only the most significant spectral bands β′, β, and ρ are shown. The symbols β′, β, and ρ were given by Clar2 to characterize the UV−vis spectral bands of PAHs. The complete list of names for the PAH structures is included in the Supporting Information section (Figure S1). The black lines connecting rings denote the movement of the aromatic sextets.

maximum absorbance of the p and β bands in the UV−vis spectra of the peri-condensed PAHs C32H16. As an extra assignment for the method, the calculation of the locations of maximum absorbance of the p and β bands in the UV−vis spectrum of the remaining C26H16 cata-condensed PAH, XVI, with no reference standard available, with only bay structural regions, and thus, with no anticipated carcinogenic potential, will also be performed. It is expected that the results achieved through the annellation theory methodology will provide reliable information about the locations of maximum absorbance of the p and β bands in the UV−vis spectra of the eight C26H16 cata-condensed PAHs under consideration. It is the first time that the locations of maximum absorbance of the p and β bands in the UV−vis spectra of dibenzo[c,m]tetraphene, XVI; naphtho[1,2-c]chrysene, XXVII; dibenzo[c,f ]tetraphene, XXVIII; benzo[f ]picene, XXIX; naphtho[2,1a]tetraphene, XXX; naphtho[2,1-c]tetraphene, XXXI; dibenzo[c,l]chrysene, XXXII; and naphtho[1,2-a]tetraphene, XXXVI, are reported.

Thus, it is apparent that magnitude and shape of the UV−vis spectral bands are key factors that differentiate the UV−vis spectra of the cata-condensed PAHs from the UV−vis spectra of the peri-condensed PAHs. In addition, the locations of maximum absorbance of the bands in the UV−vis spectra provide insightful information about the identity of a PAH molecule. However, a relationship that leads to a successful comparison between the average values of the location of maximum absorbance for cata-condensed behavior and the corresponding average values for peri-condensed behavior cannot be established due to the large variability in values reported for each PAH class. For cata-condensed PAHs, the location of maximum absorbance of the longest β band covers a range from 221 to 391 nm, and the location of maximum absorbance of the longest p band covers a range from 284 to 582 nm.2 On the other hand, for peri-condensed PAHs, the location of maximum absorbance of the longest β band covers a range from 251 to 486 nm, and the location of maximum absorbance of the longest p band covers a range from 328 to 738 nm.2 Due to this challenging scenario, the annellation, i.e., the addition (or subtraction) of rings to certain positions of the rings that form a molecule, e.g., PAH, and the direct application of this concept in the methodology named the annellation theory2 will be used for the calculation of the locations of maximum absorbance of the p and β bands in the UV−vis spectra of the seven C26H16 cata-condensed PAHs, XXVII, XXVIII, XXIX, XXX, XXXI, XXXII, and XXXVI, with no reference standards available and with prospective biological activity. The predictive power of the annellation theory was already presented, discussed, validated, and applied in a preceding article12 for the calculation of the locations of

2. THEORETICAL METHODS 2.1. Overall Procedure. Analogous to the procedure for calculation of the locations of maximum absorbance of the p and β bands in the UV−vis spectra of the C32H16 pericondensed PAHs,12 the procedure for calculation of the locations of maximum absorbance of the p and β bands in the UV−vis spectra of the C26H16 cata-condensed PAHs is composed of validation, elucidation, and substantiation. Validation involves the comparison of the locations of maximum absorbance of the p and β bands calculated using the annellation theory technique shown in Figure 412 and the locations of maximum absorbance of the p and β bands 10453


Article


be structurally and aromatically enclosed in PAH 3 so as to connect the top and the bottom part of the scheme. 2. Calculation of the difference between the locations of maximum absorbance of the p bands and the difference between the locations of maximum absorbance of the β bands of the reference PAHs 1 and 2. 3. Addition of the calculated differences (from Step 2) to the locations of maximum absorbance of the p bands and to the locations of maximum absorbance of the β bands of the reference PAH 3 to find the locations of maximum absorbance of the p and β bands in the UV−vis spectrum of PAH 4. 2.3. ZINDO/S Semiempirical Calculations. ZINDO/S semiempirical calculations were carried out to determine the locations of maximum absorbance of the p and β bands for the 37 C26H16 cata-condensed PAHs. Geometry optimization of the PAH systems was first carried out by performing force fieldbased minimization using the energy minimization panel in the Cerius 2 program17 and the COMPASS (Condensed-Phase Optimized Molecular Potentials for Atomistic Simulation Studies)18,19 consistent force field as implemented in the Cerius 2 package. The excited electronic states for the PAH systems were then calculated using the ZINDO/S20 approach, which is a semiempirical electronic structure method calibrated for calculating excited states, as implemented in the Cerius 2 program, using the COMPASS force field geometry optimized structures. This method has provided satisfactory agreement with experimental values for the calculation of optical properties of PAHs. We have previously demonstrated12,21 that values calculated for the electronic transitions of PAHs using the ZINDO/S methodology present deviations of 33 nm or less.

Figure 4. Annellation theory method introduced in ref 12 for the prediction of the locations of maximum absorbance of the p and β bands in the UV−vis spectra of the peri-condensed PAHs C32H16. Red line denotes structural and aromatic enclosure. Black line denotes the structural and aromatic relationship.

available for the already synthesized 29 C26H16 cata-condensed PAHs (ref 2 reports the UV−vis spectra of II, IV, V, VI, VII, VIII, IX, X, XI, XII, XIV, XVIII, XX, and XXXVII; ref 5 reports the UV−vis spectrum of XVII; ref 6 reports the UV−vis spectra of XXI and XXV; ref 7 reports the UV−vis spectrum of XXII; ref 8 reports the UV−vis spectra of XXIII and XXXIII; ref 9 reports the UV−vis spectra of XXIV, XXVI, and XXXIV; ref 10 reports the UV−vis spectrum of XXXV; ref 13 reports the UV− vis spectrum of I; ref 14 reports the UV−vis spectrum of III; ref 15 reports the UV−vis spectrum of XIII; ref 16 reports UV−vis spectrum of XV; and the UV−vis spectrum of XIX comes from unreported results by W. Schmidt, Institut fur PAH-Forschung, Greifenberg, Germany). Next, elucidation involves the calculation of the locations of maximum absorbance of the p and β bands in the UV−vis spectra of the eight C26H16 cata-condensed PAHs with no available syntheses procedures using the annellation theory method shown in Figure 4. Finally, substantiation comprises the comparison among the reference standards available, the annellation theory calculations, and the ZINDO/S methodology for the locations of the p1 and β1 bands in the UV−vis spectra of the 37 C26H16 catacondensed PAHs. 2.2. Mathematical Technique. The mathematical technique based on the annellation theory illustrated in Figure 4 for the calculation of the locations of maximum absorbance of the p and β bands in the UV−vis spectrum of PAH 4, using as references PAHs 1, 2, and 3, has the following steps:12 1. Determination of the structures of the reference PAHs 1, 2, and 3 that satisfy the restrictions of structural and aromatic relationship between PAHs 1 and 2, and PAHs 3 and 4, and the restriction of structural and aromatic enclosure between PAHs 1 and 3. The structural relationship, given by the shape of the molecules, and the aromatic relationship, given by the positions of the sextets and double bonds, between PAHs 1 and 2 should be equivalent to the respective structural-aromatic relationship between PAHs 3 and 4. Also, PAH 1 should

3. DISCUSSION AND RESULTS 3.1. Validation. As shown in Figure 5, the calculation of the locations of maximum absorbance of the p and β bands in the UV−vis spectra of the previously synthesized 29 C26H16 catacondensed PAHs is performed using the mentioned annellation theory technique. The comparison between the available and the calculated locations of maximum absorbance of the p and β bands in the UV−vis spectra of the 29 C26H16 cata-condensed PAHs is shown in Figure 6. A special case occurs for compound XXV in which the reported synthesis6 indicates the lack of a purified product for spectral characterization because of secondary oxidation reactions. Although the locations of maximum absorbance of the p and β bands in the UV−vis spectrum of XXV have been calculated in Figure 5, due to this synthesis uncertainty, the reported locations of maximum absorbance of the p and β bands for XXV have not been taken into account in Figure 6 and in the subsequent statistical comparisons. The complete numerical data for Figure 6 are included in the Supporting Information (Tables S1 and S2). The results demonstrate a satisfactory agreement between the available and the calculated locations for the p bands (p1, p2, and p3); and for the β bands (β1, β2, and β3) with average differences, δ̅ (δ = available−annellation theory), of +1.5 nm for the p1 bands, −0.2 nm for the p2 bands, + 1.4 nm for the p3 bands, −9.0 nm for the β1 bands, −7.2 nm for the β2 bands, and +0.8 nm for the β3 bands, where + or − indicates a higher or lower wavelength, respectively, for the location of the available maximum absorbance as compared to the maximum absorbance calculated using the annellation theory technique. 10454


Article


Figure 5. continued

10455


Article


Figure 5. Calculation of the locations of maximum absorbance of the p and β bands in the UV−vis spectra of the 29 C26H16 cata-condensed PAHs using the annellation theory method of Figure 4. The black lines connecting rings denote the movement of the aromatic sextets. 10456


Article


Figure 6. Comparison between available UV−vis spectra values (red lines) and those calculated using the annellation theory method of Figure 4 (black bars) for corresponding locations of maximum absorbance of the p bands (p1, p2, and p3) and β bands (β1, β2, and β3) of the 29 C26H16 cata-condensed PAHs.

the calculation of the locations of maximum absorbance of the p and β bands of the eight C26H16 cata-condensed PAHs (XVI, XXVII, XXVIII, XXIX, XXX, XXXI, XXXII, and XXXVI). 3.3. Substantiation. The ZINDO/S methodology explained in the Theoretical Methods section is applied for the calculation of the locations of maximum absorbance of the p1 and β1 bands of the eight C26H16 cata-condensed PAHs. The results of the application of the ZINDO/S methodology are presented in Figure 8A. The comparison between the calculated locations of maximum absorbance of the p1 and β1 bands in the UV−vis spectra of the eight cata-condensed PAHs using the annellation theory method and the ZINDO/S methodology is presented in Figure 8B. The comparison indicates average differences δ̅2 (δ2 = annellation theory − ZINDO/S) of +10 nm and +4 nm in the locations of maximum absorbance of the p1 and β1 bands, where + or − indicates a higher or lower wavelength, respectively, for the location of the maximum absorbance using the annellation theory as compared to the maximum absorbance calculated using the ZINDO/S methodology. The most pronounced effect occurs for XXVIII with differences δ2 of +48 nm for the p bands and +19 nm for the β bands. On the other hand, the slightest effect occurs for XXVII with differences δ2 of −1 nm for the p bands and −9 nm for the β bands.

A key factor affecting the locations of maximum absorbance of the p and β bands in the UV−vis spectra of the C26H16 catacondensed PAHs calculated with the annellation theory technique is planarity. Planar cata-condensed PAHs I, II, III, IV, V, VI, VII, VIII, IX, X, XI, XII, XIII, XIV, and XV present a negligible average difference, δ̅, of −0.1 nm for the p bands (average of p1, p2, and p3) and a negligible average difference, δ̅, of −2.6 nm for the β bands (average of β1, β2, and β3). On the other hand, nonplanar cata-condensed PAHs XVII, XVIII, XIX, XX, XXI, XXII, XXIII, XXIV, XXV, XXVI, XXXIII, XXXIV, XXXV, and XXXVII present a negligible average difference, δ̅, of +2.8 nm for the p bands (average of p1, p2, and p3) and a minor average difference, δ̅, of −8.1 nm for the β bands (average of β1, β2, and β3). Thus, the transition from planar to nonplanar in C26H16 cata-condensed PAHs does not significantly alter the average difference between the available and the calculated locations of maximum absorbance of the p bands, but changes to some extent (−5.5 nm) the average difference between the available and the calculated locations of maximum absorbance of the β bands. 3.2. Elucidation. Once the annellation theory technique for the calculation of the locations of maximum absorbance of the p and β bands in the UV−vis spectra of the C26H16 catacondensed PAHs is validated using the analysis performed in section 3.1., the technique is used, as described in Figure 7, for 10457


Article


Figure 7. Calculation of the locations of maximum absorbance of the p and β bands in the UV−vis spectra of the eight C26H16 cata-condensed PAHs with no UV−vis spectra available using the annellation theory method of Figure 4. The black lines connecting rings denote the movement of the aromatic sextets.

Figure 8. (A) Locations of maximum absorbance of the p1 and β1 bands of the eight cata-condensed C26H16 PAHs with unknown UV−vis spectra calculated using the ZINDO/S methodology. (B) Comparison of the locations of maximum absorbance of the p1 and β1 bands of the eight catacondensed C26H16 PAHs with unknown UV−vis spectra calculated using the annellation theory procedure shown in Figure 7 (black bars) and the ZINDO/S methodology (green bars). The complete list of names for the PAH structures is included in the Supporting Information (Figure S1). The black lines connecting rings denote the movement of the aromatic sextets.

10458


Article


using the annellation theory and the ZINDO/S methodology with respect to the locations of the β1 bands from reference standards. 3.4. Overlapping. During the calculation of the locations of maximum absorbance of the p and β bands in the group of 37 C26H16 cata-condensed PAHs illustrated in Figures 5 and 7, there were cases, e.g., II, XXII, and XXIX, in which the locations of maximum absorbance of one or more of the longest wavelength β bands overlapped the locations of maximum absorbance of one or more of the lowest wavelength p bands. In these cases, it is anticipated that the β bands would prevail over the p bands due to the high β/p absorbance intensity ratio in cata-condensed PAHs (as it was stated in the introduction) and thus, only one or two of the most prominent p bands would be observed.

In addition, the comparison between the annellation theory calculations in Figure 5 and the ZINDO/S calculations for the locations of the p1 and β1 bands in the UV−vis spectra of the 29 C26H16 cata-condensed PAHs with available reference standards illustrated in the Supporting Information (Table S3) is consistent with the above-mentioned shifts. Average differences δ̅2 of +16 nm and +10 nm in the locations of maximum absorbance of the p1 and β1 bands are observed. The ZINDO/S theoretical estimates are derived from a single “frozen” molecule in the gas phase at 0 K without corrections for thermal motions and solvent effects. The difference between the locations of maximum absorbance of the p1 and β1 bands of the cata-condensed PAHs as calculated using the annellation theory method versus the ZINDO/S methodology, could be due to the Stokes shift, which involves the reconfiguration of the solvent cage for the ground electronic state once the excited PAH molecule undergoes photoemission.34,35 The Stokes shift to the red is reported to be around 10−45 nm for solvents with low polarity. An instructive comparison among the reference standards available, the annellation theory calculations, and the ZINDO/S methodology for the locations of the p1 and β1 bands in the UV−vis spectra of the 29 C26H16 cata-condensed PAHs is shown in Figure 9. The complete numerical data for Figure 9

4. CONCLUSIONS Using the annellation theory, the locations of maximum absorbance of the p and β bands in the UV−vis spectra were calculated for eight C26H16 cata-condensed PAHs, XVI, XXVII, XXVIII, XXIX, XXX, XXXI, XXXII, and XXXVI, for which synthesis procedures are not available. Initially, the annellation theory procedure was validated by comparing the calculated locations of the p and β bands in the UV−vis spectra with the respective locations of the p and β bands available for 29 isomers in the C26H16 cata-condensed group. The results for 29 of the 37 isomers with available UV−vis spectra showed satisfactory average differences, δ̅, of +1.5 nm for the p1 bands, −0.2 nm for the p2 bands, + 1.4 nm for the p3 bands, −10 nm for the β1 bands, −7.2 nm for the β2 bands, and +0.8 nm for the β3 bands. Also, planar cata-condensed PAHs I, II, III, IV, V, VI, VII, VIII, IX, X, XI, XII, XIII, XIV, and XV present a negligible average difference, δ̅, of −0.1 nm for the p bands (average of p1, p2, and p3) and a negligible average difference, δ̅, of −2.6 nm for the β bands (average of β1, β2, and β3). On the other hand, nonplanar cata-condensed PAHs XVII, XVIII, XIX, XX, XXI, XXII, XXIII, XXIV, XXV, XXVI, XXXIII, XXXIV, XXXV, and XXXVII present a negligible average difference, δ̅, of +2.8 nm for the p bands (average of p1, p2, and p3) and a minor average difference, δ̅, of −8.1 nm for the β bands (average of β1, β2, and β3). With respect to the agreement between the locations of the p and β bands in the UV−vis spectra of the eight C26H16 catacondensed PAHs calculated using the annellation theory method and the corresponding locations determined using the ZINDO/S semiempirical calculations, the average differences, δ̅, of +10 nm and +4 nm for the p1 and β1 bands were acceptable and likely related to the Stokes shift (10 to 45 nm to longer wavelengths for solvents with low polarity). As a final point, the locations of the p1 and β1 bands in the UV−vis spectra of 29 cata-condensed PAHs calculated with the annelation theory and the ZINDO/S methodology are consistent with the locations from reference standards available with average percent differences of 3% (annellation theory) and 5% (ZINDO/S) for the p1 bands, and 4% (annellation theory) and 3% (ZINDO/S) for the β1 bands. This is the first report of the locations of maximum absorbance of the p and β bands in the UV−vis spectra of the eight C26H16 cata-condensed isomers dibenzo[c,m]tetraphene, XVI; naphtho[1,2-c]chrysene, XXVII; dibenzo[c,f ]tetraphene, XXVIII; benzo[f ]picene, XXIX; naphtho[2,1a]tetraphene, XXX; naphtho[2,1-c]tetraphene, XXXI; dibenzo[c,l]chrysene, XXXII; naphtho[1,2-a]tetraphene, XXXVI. These PAHs might present carcinogenic potential, except

Figure 9. Comparison of the locations of the p1 bands (top) and β1 bands (bottom) in the UV−vis spectra of the 29 C26H16 catacondensed PAHs using reference standards available (red crosses), the annellation theory calculations (black diamonds), and the ZINDO/S methodology (green squares).

are included in the Supporting Information (Table S3). The comparison indicates average percent differences of 3% and 5% between the locations of the p1 bands calculated using the annellation theory and the ZINDO/S methodology with respect to the locations of the p1 bands from reference standards. Additionally, there are average percent differences of 4% and 3% between the locations of the β1 bands calculated 10459



■ ■ ■

ACKNOWLEDGMENTS Y.R.-M. acknowledges the support under projects D.61017 and D.61006 of the Instituto Mexicano del Petróleo.

XVI; therefore it is important the elucidation of their optical properties here presented. The characterization of PAHs with unknown synthesis procedures using the annellation theory will support current experimental efforts to understand asphaltenes structure. Petroleum asphaltenes are polycyclic aromatic compounds similar to PAHs but containing heteroatoms (N, O, S) and alkyl side chains in their structure. The elucidation of asphaltene structures is fundamental to be able to understand their interfacial chemistry. There has been a long-standing debate about asphaltenes structure and architecture. Very recently, based on advanced imaging technique, Schuler et al.36 have presented atomic force microscopy (AFM) images of 100 asphaltene molecules, including coal and some oil asphaltenes, which represented major advance in the understanding of asphaltene structures. Crude oil and asphaltene absorption spectra exhibit similar properties, and the PAHs in heavier crude oils and asphaltenes are known to be the source of the color of heavy oils.37−41 Therefore, understanding the electronic bands of PAHs is becoming increasingly important. The optical properties of asphaltenes is of significant importance to obtain a better understanding of their structure and therefore of their surface activity as stabilizers of oil−water emulsions. Also, enhanced oil recovery requires disrupting the wettability of the oil-mineral surface. Asphaltenes play a major role in the oil-mineral interfacial chemistry. Understanding their structure is fundamental to be able to understand their interfacial chemistry.

■

ABBREVIATIONS IUPAC, International Union of Pure and Applied Chemistry REFERENCES

(1) Sander, L. C.; Wise, S. A. NIST Special Publication 922: Polycyclic Aromatic Structure Index; National Institute of Standards and Technology: Gaithersburg, MD, 1997. (2) Clar, E. Polycyclic Hydrocarbons; Academic Press: New York, 1964. (3) Oña-Ruales, J. O.; Ruiz-Morales, Y. Extended Y-Rule Method for the Characterization of the Aromatic Sextets in Cata-Condensed Polycyclic Aromatic Hydrocarbons. J. Phys. Chem. A 2014, 118, 12262−12273. (4) Sharma, A. K.; Amin, S. Synthesis and Identification of Major Metabolites of Environmental Pollutant Dibenzo[c,mno]Chrysene. Chem. Res. Toxicol. 2005, 18, 1438−1443. (5) Sharma, A. K.; Lin, J. M.; Desai, D.; Amin, S. Convenient Syntheses of Dibenzo[c,p] Chrysene and its Possible Proximate and Ultimate Carcinogens: In Vitro Metabolism and DNA Adduction Studies. J. Org. Chem. 2005, 70, 4962−4970. (6) Laarhoven, W. H.; Cuppen, T. H. J. H. M.; Nivard, R. J. F. Photodehydrocyclizations in Stilbene-Like CompoundsIII: Effect of Steric Factors. Tetrahedron 1970, 26, 4865−4881. (7) Clar, E.; McAndrew, B. A.; Stephen, J. F. The Electronic Interaction in Benzologues of Pyrene. Tetrahedron 1970, 26, 5465− 5478. (8) Tinnemans, A. H. A.; Laarhoven, W. H. Photodehydrocyclizations in Stilbene-Like Compounds. X. Rearrangements in the Photocyclization of 4, 5-Diphenyltriphenylene and 4, 5-Diphenylphenanthrene. J. Am. Chem. Soc. 1974, 96, 4617−4622. (9) Brison, J.; Martin, R. H. Synthèse, Par la Méthode de Hewett, Des Benzo[a]Naphto[2,1-j] Anthracéne, Naphto[2,1-c]Chrysene, Benzo[a]Picéne et 8,16-Diméthoxycarbonylbenzo[c]Naphto[2,1−1]. Bull. Soc. Chim. Belg. 1983, 92, 893−899. (10) Grellmann, K. H.; Hentzschel, P.; Wismontski-Knittel, T.; Fischer, E. The Photophysics and Photochemistry of Pentahelicene. J. Photochem. 1979, 11, 197−213. (11) Fetzer, J. C. Large (C ≥ 24) Polycyclic Aromatic Hydrocarbons: Chemistry and Analysis; Wiley-Interscience: New York, 2000. (12) Oña-Ruales, J. O.; Ruiz-Morales, Y. The Predictive Power of the Annellation Theory: The Case of the C32H16 Benzenoid Polycyclic Aromatic Hydrocarbons. J. Phys. Chem. A 2014, 118, 5212−5227. (13) Angliker, H.; Rommel, E.; Wirz, J. Electronic Spectra of Hexacene in Solution (Ground State. Triplet State. Dication and Dianion). Chem. Phys. Lett. 1982, 87, 208−212. (14) Lang, K. F. Pure Products from Coal Tar. Angew. Chem. 1951, 63, 345−349. (15) Clar, E.; Kelly, W. 2:3-Benzopicene and Naphtho(2′:3′-1:2) chrysene. J. Chem. Soc. 1957, 4163−4166. (16) Marsili, A. Condensation of 2-Benzoylbenzoic with 2-Naphthylacetic Acid and Synthesis of Benzo[a]Pentaphene. J. Org. Chem. 1967, 32, 240−241. (17) Cerius 2, version 4.6, Accelrys Inc.: San Diego, CA, 2001. (18) Sun, H.; Ren, P.; Fried, J. R. The COMPASS Force Field: Parameterization and Validation for Polyphosphazenes. Comput. Theor. Polym. Sci. 1998, 8, 229−246. (19) Sun, H. COMPASS: An Ab Initio Force-Field Optimized for Condensed-Phase Applications-Overview with Details on Alkane and Benzene Compounds. J. Phys. Chem. B 1998, 102, 7338−7364. (20) Correa de Mello, P.; Hehenberger, M.; Zerner, M. C. Converging SCF Calculations on Excited States. Int. J. Quantum Chem. 1982, 21, 251−258. (21) Ruiz-Morales, Y. HOMO−LUMO Gap as an Index of Molecular Size and Structure for Polycyclic Aromatic Hydrocarbons

ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.jpca.5b07681. Names corresponding to the PAH structures analyzed in the article, calculated and available locations of maximum absorbance of the p1, p2, p3, β1, β2, and β3 bands in the UV−vis spectra of 29 C26H16 cata-condensed PAHs, and comparison among the reference standards available, the annellation theory calculations, and the ZINDO/S methodology for the locations of the p1 and β1 bands in the UV−vis spectra of 29 C26H16 cata-condensed PAHs (PDF)

■

Article

AUTHOR INFORMATION

Corresponding Author

*Guest Researcher, National Institute of Standards and Technology, NIST, 100 Bureau Drive, Mail Stop 8390, Gaithersburg, Maryland 20899. E-mail: [email protected]. Author Contributions

The manuscript was written through contributions of all authors. All authors have given approval to the final version of the manuscript. Notes

The authors declare no competing financial interest. Certain commercial equipment, instruments, or materials (or suppliers, or software, ...) are identified in this paper to foster understanding. Such identification does not imply recommendation or endorsement by the National Institute of Standards and Technology, NIST, nor does it imply that the materials or equipment identified are necessarily the best available for the purpose. 10460


Article

The Journal of Physical Chemistry A (PAHs) and Asphaltenes: A Theoretical Study. I. J. Phys. Chem. A 2002, 106, 11283−11308. (22) Somers, M. L.; Wornat, M. J. UV Spectral Identification of Polycyclic Aromatic Hydrocarbon Products of Supercritical 1Methylnaphthalene Pyrolysis. Polycyclic Aromat. Compd. 2007, 27, 261−280. (23) Erünlü, R. K. Synthesen von Benzo-Naphtho-Phenalenen und Benzo-Naphtho-Pyrenen. Chem. Ber. 1965, 98, 743−755. (24) Zander, M.; Franke, W. H. Mehrkernige Aromatische Systeme Durch Diensynthesen mit Chrysenchinon-(2.8). Chem. Ber. 1968, 101, 2404−2408. (25) Friedel, R. A.; Orchin, M. Ultraviolet Spectra of Aromatic Compounds; Wiley: New York, 1952. (26) Masonjones, M. C. Kinetic Control of Polyaryl Formation in a Pyrolysis Environment. Ph.D. Thesis, Massachusetts Institute of Technology, 1995. (27) Anderson, D. M. W.; Campbell, N.; Leaver, D.; Stafford, W. H. Syntheses of 1-Phenylfluorene and 1-and 3-Phenylphenanthrene. J. Chem. Soc. 1959, 3992−3997. (28) Babayan, V. O.; Zagorets, P. A.; Tatevosyan, G. T. Synthesis of Hydrocarbons of 1,2-Benzanthracene Series. Zh. Obshch. Khim. 1953, 23, 1214−1220. (29) Clar, E.; Guye-Vuilleme, J. F.; Stephen, J. F. Higher Annellated 1:2,7:8-Dibenzochrysenes. Tetrahedron 1964, 20, 2107−2117. (30) Friedel, R. A.; Orchin, M.; Reggel, L. Steric Hindrance and Short Wave Length Bands in the Ultraviolet Spectra of Some Naphthalene and Diphenyl Derivatives. J. Am. Chem. Soc. 1948, 70, 199−204. (31) Zander, M.; Franke, W. H. 1.12; 4.5-Dibenzo-Perylen und 1.12Benzo−[Naphtho-2″″.3″:4.5-Perylen]. Chem. Ber. 1966, 99, 1275− 1278. (32) Blümer, G. P.; Gundermann, K. D.; Zander, M. Zur Umsetzung von Polycyclischen Aromatischen Kohlenwasserstoffen mit Benzol und Aluminiumchlorid. Chem. Ber. 1976, 109, 1991−2000. (33) Vingiello, F. A.; Henson, P. D. 7-Phenyldibenz[a,h]anthracene and Benzo[e]Naphtho[1,2-b]pyrene. J. Org. Chem. 1965, 30, 2842− 2845. (34) Berlman, I. B. Handbook of Fluorescence Spectra of Aromatic Molecules; Academic Press: New York, 1971. (35) Lakowicz, J. R. Principles of Fluorescence Spectroscopy; Springer: New York, 2006. (36) Schuler, B.; Meyer, G.; Peña, D.; Mullins, O. C.; Gross, L. Unraveling the Molecular Structures of Asphaltenes by Atomic Force Microscopy. J. Am. Chem. Soc. 2015, 137, 9870−9876. (37) Ruiz-Morales, Y.; Mullins, O. C. Singlet−Triplet and Triplet− Triplet Transitions of Asphaltene PAHs by Molecular Orbital Calculations. Energy Fuels 2013, 27, 5017−5028. (38) Klee, T.; Masterson, T.; Miller, B.; Barrasso, E.; Bell, J.; Lepkowicz, R.; West, J.; Haley, J. E.; Schmitt, D. L.; Flikkema, J. L.; et al. Triplet Electronic Spin States of Crude Oils and Asphaltenes. Energy Fuels 2011, 25, 2065−2075. (39) Ruiz-Morales, Y.; Mullins, O. C. Polycyclic Aromatic Hydrocarbons of Asphaltenes Analyzed by Molecular Orbital Calculations with Optical Spectroscopy. Energy Fuels 2007, 21, 256−265. (40) Alvarez-Ramírez, F.; Ruiz-Morales, Y. Island versus Archipelago Architecture for Asphaltenes: Polycyclic Aromatic Hydrocarbon Dimer Theoretical Studies. Energy Fuels 2013, 27, 1791−1808. (41) Juyal, P.; McKenna, A. M.; Yen, A.; Rodgers, R. P.; Reddy, C. M.; Nelson, R. K.; Andrews, A. B.; Atolia, E.; Allenson, S. J.; Mullins, O. C.; et al. Analysis and Identification of Biomarkers and Origin of Color in a Bright Blue Crude Oil. Energy Fuels 2011, 25, 172−182.

10461


The Predictive Power of the Annellation Theory: The Case of the

Recommend Documents