A Combined Experimental and Theoretical Study of Phenol-(Acetylene)N (N 7) Clusters

Supplementary material for :

A Combined Experimental and Theoretical Study of Phenol-(Acetylene)n (n ≤ 7) Clusters.

GurmeetSingh,aApurbaNandi,a Shridhar R. Gadrea,b* and Takashi Chiba,cAsukaFujiic*

aDepartment of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208016, India

bInterdisciplinary School of Scientific Computing, SPPU, Pune-411007, India

cDepartment of Chemistry, Tohoku University, Sendai 980-8578, Japan

Email: ,

Supporting Information for experiment:

Evaluation of the maximum size uncertainty in infrared spectroscopy

Because clusters usually suffer from fragmentations in an ionization process, it is difficult to precisely measure the size distribution of neutral clusters only from ionization combined with mass spectrometry. However, for phenol-(acetylene)n, the maximum number of evaporated acetylene molecules (Δn) upon the two-color resonance-enhanced ionization can be roughly estimated by the energetics calculations.

We assume the sequential evaporation of acetylene one by one upon the ionization. Then, the maximumΔn is evaluated by

maximumΔn = Eexcess/ D(D0) (1)

where Eexcess is the maximum excess energy upon the ionizations and D(D0) is the dissociation energy of the one acetylene loss channel in the cationic state. Eexcess is given by:

Eexcess = [E(UV)+E(UV2)] – IP[phenol-(acetylene)n] (2)

where E(UV1) and E(UV2) are the UV photon energies (36354 and 31740 cm−1, respectively), and IP[phenol-(acetylene)n] is the adiabatic ionization energy of phenol-(acetylene)n.

The correct value of D(D0) should depend on the cluster size, and its precise evaluation is practically difficult. Therefore, here we assume that the value is approximated by the dissociation energy of one acetylene molecule from an (acetylene)n cluster of n ~4. Then, it is estimated to be ~9 kJ/mol (~750 cm-1) from the previously reported binding energy of (acetylene)n clusters at the CCSD(T)/CBS level.1

The value of IP[phenol-(acetylene)n] is given by

IP[phenol-(acetylene)n] = IP(phenol) – [D’(D0) - D’(S0)] (3)

where, IP(phenol) is the adiabatic ionization energy of bare phenol (68625 cm-1),2D’(D0) is the binding energy between phenol+ cation and (acetylene)n, and D’(S0) is the binding energy between neutral phenol and (acetylene)n. The value of [D’(D0) - D’(S0)] is roughly estimated by the scaling of the value in phenol-(H2O)n. Here we assume that the magnitude of the redshift of the phenolic OH stretch frequency in the cluster is a measure of the interaction energy between phenol and (acetylene)n or (H2O)n moiety (Badger-Bauer rule).3 The redshift of the OH frequency of phenol-H2O is about twice larger than that in phenol-acetylene.4-6 Therefore, D’(D0), D’(S0), (and also [D’(D0) - D’(S0)]) of phenol-(acetylene)n are estimated to be about half of those of phenol-(H2O)n. The ionization energy of phenol-(H2O)n (n = 1- 12) has been observed,7 and [D’(D0) - D’(S0)] in phenol-(H2O)n is converged to ~6000 cm-1. Therefore, we evaluate [D’(D0) - D’(S0)] in phenol-(acetylene)n to be ~3000 cm-1.

On the basis of these estimated values and Eqs. (2) and (3), Eexess is estimated to be ~2500 cm-1. Thus, from eq.(1), maximum Δn is estimated to be ~3.3.

References

1. S. Karthikeyan, H. M. Lee, K. S. Kim, J. Chem. Theory Comput. 6, 3190 (2010).
2. O. Dopfer, K. Müller-Dethlefs, J. Chem. Phys. 101, 8508 (1994).
3. P. Banerjee, D. P. Mukhopadhyay, T. Chakraborty, J. Chem. Phys. 143, 204306 (2015).
4. T. Watanabe, T. Ebata, S. Tabnabe, N. Mikami, J. Chem. Phys. 105, 408 (1996).
5. A. Fujii. T. Ebata, N. Mikami, J. Phys. Chem. A106, 8554 (2002).
6. M. Böning, B. Stuhlmann, G. Engler, K. Kleinermanns, J. Phys. Chem. A117, 3214 (2013).
7. K. Kleinermanns, Ch. Janzen, D. Spangenberg, M. Gerhards, J. Phys. Chem. A103, 5232 (1999).

Table S1: Cartesian coordinates (in Å) for the reported isomers of Ph(Ac)n cluster for n = 1, 2, 4, 6 and 7 optimized at MP2/aug-cc-pVDZ level of theory

Table S2: Cartesian coordinates (in Å) for the reported isomers of Ph(Ac)n cluster for n = 1, 2, 4, 6 and 7 optimized at B97-D/aug-cc-pVDZ level of theory

Table S3: Energies (EB97-D/aVDZ); ZPE-corrected Energies (EZPE/Corrected); the sum of electronic and thermal energies, U;the sum of electronic and thermal enthalpies, H and the sum of electronic and thermal free energies, Gof the best four isomers of Ph(Ac)n (n = 6 and7) optimized at B97-D/aug-cc-pVDZ (aVDZ) level of theory. The thermal parameters (in a.u.) are calculated by using the Gaussian33 package at the default temperature of 298.15 K.

FigureS1:Four lowest energy isomers of Ph(Ac)n(n=1 and 2) clusters, optimized at B97-D/aVDZ level of theory. See text and Table 2 for details.

Figure S2:Four lowest energy isomers of Ph(Ac)n(n=4 and 6) clusters, optimized at B97-D/aVDZ level of theory. See text and Table 2 for details.

Figure S3: Vibrational IR-Spectra for Ph(Ac)n cluster for n = 1, 2, and 4 optimized at MP2/aug-cc-pVDZ level of theory.

Figure S4: Grafted-MTA based vibrational IR-Spectra for Ph(Ac)n cluster for n = 6 and 7 calculatedat MP2/aug-cc-pVDZ level of theory.

Figure S5: Vibrational IR-Spectra for Ph(Ac)n cluster for n = 4, 6 and 7 calculated at B97-D/aug-cc-pVDZ level of theory.

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