Salt Cluster Attachment to Crown Ether Decorated Phthalocyanines in

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Salt Cluster Attachment to Crown Ether Decorated Phthalocyanines in the Gas Phase Ina D Kellner, Uwe Hahn, Tomas Torres, and Thomas Drewello J. Phys. Chem. A, Just Accepted Manuscript • DOI: 10.1021/acs.jpca.7b10156 • Publication Date (Web): 22 Jan 2018 Downloaded from http://pubs.acs.org on January 22, 2018

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The Journal of Physical Chemistry

Salt Cluster Attachment to Crown Ether decorated Phthalocyanines in the Gas Phase Ina D. Kellner1), Uwe Hahn2, a), Tomás Torres2–4) and Thomas Drewello*1)

1) Physical Chemistry I, Department of Chemistry and Pharmacy, University of ErlangenNürnberg, Egerlandstraße 3, 91058 Erlangen, Germany 2) Department of Organic Chemistry, Faculty of Science, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain 3) Instituto Madrileño de, Estudios Avanzados (IMDEA)-Nanociencia, c/Faraday, 9, Cantoblanco, 28049 Madrid, Spain 4) Institute for Advanced Research in Chemical Sciences (IAdChem), Universidad Autónoma de Madrid, 28049 Madrid, Spain

* Corresponding author: [email protected]; phone: +49 9131 85 28312

a

Current address: Laboratoire de Chimie des Matériaux Moléculaires, Université de Strasbourg and CNRS (UMR 7509), Ecole Européenne de Chimie, Polymères et Matériaux (ECPM), 25 rue Becquerel, 67087 Strasbourg, France 1 ACS Paragon Plus Environment

The Journal of Physical Chemistry 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Abstract Crown ether decorated phthalocyanines were designed to form rigidly eclipsed aggregates with metal ions being sandwiched between the molecules. We studied tetra-[18]crown-6 ether functionalized zinc phthalocyanine (ZnPcTetCr) in the presence of excess NaCl by electrospray ionization mass spectrometry (ESI-MS). ZnPcTetCr was found to form aggregates in the gas phase to which several neutral NaCl molecules are attached. Collisioninduced dissociation (CID) experiments revealed that the ions observed in the positive and negative ion mode possess remarkably different structures. Their fragmentation behavior indicates that the sodium ions providing the charge of the positively charged aggregates are strongly bound inside the crown ether moieties, while the neutral salt units are less strongly attached. However, in the negatively charged ions, none of the sodium ions is embedded in the crown ether moieties, the NaCl molecules were found to be attached as one large, weakly bound cluster.

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Chart 1. Structure of ZnPcTetCr (M).

Introduction Phthalocyanines (Pcs) and their derivatives are well known for their aggregation in solution.1 With the aim of creating well-defined aggregates, crown ether decorated phthalocyanines (cp. Chart 1) were first synthesized in 1986 2-4 and have been studied extensively since.5-13 While Pcs usually stack with a small staggering angle (cp. Chart 2a) to increase attractive interaction between the aromatic cores,10, 14 crowned Pcs can be prompted to assume an eclipsed conformation (Chart 2b).5-11 Addition of metal cations which are larger than the crown ether cavities leads to the stepwise formation of cofacial dimers and oligomers (Chart 2b). In these aggregates, the metal ions are shared between two crown ether units (sandwich complex), forcing the Pc cores into a rigidly eclipsed conformation. Increasing the salt concentration leads to separation of the sandwich complexes and a staggered conformation, as more crown ether moieties are occupied and charge repulsion between the positively charged sites controls the structure (Chart 2c).10, 15 If the added cations are small enough to be embedded in the crown ether cavities, only monomers and, in some cases, non-cofacial dimers are observed in solution.5, 7-9



Chart 2. Stacking of crown ether decorated phthalocyanines (simplified schematic) in solution a) without metal ions, b) with cations and c) with excess metal ions.

We recently studied the aggregation of the tetra-[18]crown-6 ether functionalized zinc phthalocyanine (ZnPcTetCr, M) in the gas phase with electrospray mass spectrometry (ESIMS).16 Even in the absence of metal ions, these Pcs form singly and multiply charged aggregates consisting of neutral molecules and radical cations. In the present investigation NaCl was added to the ZnPcTetCr solution in a tenfold molar excess. The ESI mass spectra obtained with this solution showed aggregates of ZnPcTetCr containing neutral NaCl units in both polarities. While salt clusters have been studied extensively in the gas phase,17-29 their aggregates with larger molecules have rarely been addressed.30, 31 The aggregate ions observed in the positive and negative ion modes were found to behave remarkably different upon collisional activation. The fragmentation behavior of the positively charged ions indicates that the sodium ions providing the charge are strongly bound inside the crown ether moieties, while the neutral salt units are less strongly attached. However, in the negatively charged ions, none of the sodium ions is bound to a crown ether, the NaCl seems to be attached as one large, weakly bound cluster.


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Experimental Methods ZnPcTetCr was synthesized following reported procedures5, 6 and its characterization is in good agreement with the literature.32 Small amounts (0.3-0.4 mg) of ZnPcTetCr were dissolved in dichloromethane (DCM) and then diluted with acetonitrile (ACN) until a 1:1 (v:v) mixture was obtained. The solvent ratio was chosen to achieve stable spraying conditions in the ESI source. The final concentration of ZnPcTetCr was in the range of 1-5 × 10−5 mol L−1. For the cluster attachment experiments, NaCl was dissolved in methanol (1 g L−1) and added in a tenfold molar excess to the ZnPcTetCr solution. The maximum content of methanol in the final solution was 3 vol%. All solvents used were of HPLC grade purity. The majority of the ESI measurements were conducted with a quadrupole ion trap (QIT) (esquire6000, Bruker Daltonics, Bremen, Germany). The sample solution was directly injected at a flow rate of 240 μL h−1, the temperature of the nitrogen dry gas was set to 300 °C. The voltage between the needle and the capillary entrance was set to −4 kV in the positive ion mode and +4 kV in the negative ion mode, respectively. After passing the spray shield and a glass capillary, the ions are accelerated through a skimmer into the next vacuum stage. As solvent molecules and nitrogen gas are still present in this part of the transfer region, collisional activation of the ions may occur here. MSn experiments are performed inside the QIT using collision-induced dissociation (CID) employing He as the collision gas at a pressure of 4 × 10−4 Pa (as measured by the vacuum gauge; the real pressure within the trap is known to be higher by approximately two orders of magnitude)33. The isolation width and fragmentation amplitude was adjusted in each case to ensure complete dissociation of all the ions contributing to the isotopic pattern of the precursor. The relative intensities of the product ions did not change with varying amplitude. 5 ACS Paragon Plus Environment


Selected experiments were performed with an ESI quadrupole time-of-flight instrument (QTOF) (micrOTOF-Q II, Bruker Daltonics, Bremen, Germany). Due to its slightly different source geometry, a flow rate of 180 μL h−1 and a dry gas temperature of 180 °C were used in this case. Between the needle and the glass capillary a voltage of −4.5 kV (positive ion mode) or +2.8 kV (negative ion mode) was applied. The transport region of the QTOF employs two funnel ion guides to collect the ions, offering softer conditions than the skimmer region of the QIT 34-36. For MS/MS experiments N2 was used as collision gas.

Results and Discussion Positive-ion mode In a control experiment, ZnPcTetCr was first sprayed without addition of NaCl to the sample solution. The resulting ESI mass spectrum is shown in Fig. 1a (for enlargements see Fig. S1– S3 of the Supporting Information). Due to the high alkali metal affinity of the crown ether units,37-40 even minute sodium and potassium salt contamination of the solvents (DCM, ACN) results in various adducts. Overall, the Na+ adducts dominate the spectrum, K+ is only detected in mixed Na+/K+ adducts in less abundance. This might solely be the result of larger sodium contamination of the solvents, however, the host-guest interaction between the [18]crown-6 moiety and Na+ is also stronger compared to K+,40, 41 possibly contributing to the high intensity of the Na+ adducts. Note that the base peak of the mass spectrum (m/z 1537) consists mostly of the doubly charged dimer M2Na22+, the monomer MNa+ is only observed as a slight disturbance of the isotope pattern of the dimer (cp. Figure S2a of the Supporting Information). A rather peculiar doubly charged ion is detected at m/z 768. Its m/z value and isotope pattern correspond to the formula MNa(2+)• (cp. Figure S3 of the Supporting Information). It therefore consists of two different charge carriers, the sodium ion and the radical cation of the phthalocyanine. Considering the low oxidation potential of 6 ACS Paragon Plus Environment

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phthalocyanines,42 MNa(2+)• is probably generated via one-electron oxidation from the sodiated molecule in the high electric field of the spray needle.16, 43, 44

Figure 1. ESI mass spectra of ZnPcTetCr in DCM/ACN (1:1) (a) without addition of NaCl and (b) with a tenfold molar excess of NaCl.

With the addition of a tenfold molar excess of NaCl to the sample solution, the mass spectrum changes quite drastically (Fig. 1b and S4, S5 of the Supporting Information). Observed are monomers carrying up to three charges (MNa+, M(NaCl)0-7Na22+, M(NaCl)0-2Na33+), dimers with two to four charges (M2(NaCl)1-4Na22+, M2(NaCl)1-9Na33+, M2(NaCl)2-5Na44+) and trimers with three to five charges (M3(NaCl)3-6Na33+, M3(NaCl)4-11Na44+, M3(NaCl)6-8Na55+) (cp. Table 1). Apart from the singly charged monomer MNa+, all species exist with a varying number of attached neutral NaCl salts. Note that no quadruply charged monomer MNa44+ was observed. 7 ACS Paragon Plus Environment


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Table 1. Observed adducts in positive ion mode (n.o. = not observed).

monomers

dimers

trimers

ions

m/z rangea

M(NaCl)nNa+ M(NaCl)nNa22+ M(NaCl)nNa33+ M(NaCl)nNa44+ M2(NaCl)nNa22+ M2(NaCl)nNa33+ M2(NaCl)nNa44+ M3(NaCl)nNa33+ M3(NaCl)nNa44+ M3(NaCl)nNa55+

1535 779–984 527–566 401– 1567–1654 1052–1189 810–853 1616–1635 1232–1320 990–1037

observed in QIT (n = …) 0 0–7 0–2 n.o. 1–4 1–9 2–5 3–6 4–11 6–8

observed in QTOF (n = …) n.o. 0–2 0–2 n.o. n.o. 2–6 2–5 n.o. 5–8 5–9

a

Peak with the highest intensity of the smallest cluster to peak with highest intensity of largest observed cluster.

To gain insight into the structure of the ions, collision-induced dissociation (CID) mass spectra were obtained for most of them. Note that we cannot comment on the structure of the NaCl clusters themselves, as they are known to rearrange and fluctuate at relatively low activation energies prior to dissociation.29, 45 However, as will become clear in the discussion, we can infer the location of the charge carrying ions and the clusters' point of attachment to the ZnPcTetCr molecule from the CID mass spectra. A few representative examples of CID spectra are shown in the following, other selected fragmentation spectra can be found in the Supporting Information (Fig. S6–S10). The predominant dissociation pathway of the doubly charged monomer MNa22+ (m/z 779) is the loss of a sodium ion, yielding MNa+ (m/z 1535) (Fig. 2a). However, a series of doubly charged product ions is also observed, whose m/z values correspond to sequential losses of CH2O, C2H4O and C2H4 from the crown ether unit. As these fragment ions still contain two sodium ions, their existence proofs the strong bond to both Na+ ions, causing the ZnPcTetCr to dissociate rather than release the cations. The fragment ion MNa+ is also accompanied by a 8 ACS Paragon Plus Environment

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series of second-generation product ions, corresponding to similar neutral losses from the ZnPcTetCr framework. In contrast, the CID mass spectrum of the triply charged monomer MNa33+ (m/z 527) shows only loss of Na+ resulting in MNa22+ (Fig 2b). The third sodium cation is therefore less strongly bound by ZnPcTetCr, most likely due to charge repulsion. This also explains the lack of a quadruply charged monomer MNa44+ in the mass spectra (Fig. 1b).

Figure 2. CID mass spectra of a) MNa22+ (m/z 779) and b) MNa33+ (m/z 527).

Figure 3 shows two examples for the fragmentation of ions containing neutral NaCl units. The doubly charged monomer M(NaCl)3Na22+ dissociates via the loss of neutral NaCl molecules (Fig. 3a). The most abundant product ion is MNa22+. Note that we cannot discern whether the fragmentation occurs via consecutive losses of single NaCl units or via the loss of small salt clusters. In the QIT, only the precursor ion is activated, while all the fragments are cooled



down by collisions with the buffer gas.46, 47 Consecutive fragmentations should therefore only occur, if the ion retains enough excess energy after the first dissociation.

Figure 3. CID mass spectra of a) M(NaCl)3Na22+ (m/z 868) and b) M(NaCl)4Na22+ (m/z 897).

The CID mass spectrum of M(NaCl)4Na22+ is less ambiguous (Fig. 3b). The product ions M(NaCl)2Na22+ and MNa22+ are clearly obtained via the loss of one or two (NaCl)2 dimers. This fragmentation behavior has been shown to be typical for salt clusters.17, 18, 24, 31, 48 In lowenergy CID small cesium iodide clusters dissociate via consecutive losses of CsI or (CsI)2. The loss of larger clusters only occurs from larger precursor cluster ions or at high-energy CID.24 This leads us to conclude that the NaCl is weakly bound to the charged ZnPcTetCr as a small cluster, probably to the Na+ ions embedded in the crown ether moieties. The dissociation of M(NaCl)3Na22+ (Fig. 3a) therefore most likely proceeds via loss of a single salt molecule and a dimer in two successive steps.


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The consecutive loss of NaCl and/or (NaCl)2 units is observed for all the positively charged ions containing neutral salt (cp. Fig. S6–S10 of the Supporting Information). For all but the highest charged ions (M2(NaCl)nNa44+ and M3(NaCl)nNa5+, see below) it is the first dissociation step upon activation. Figure 4 shows the CID spectrum of M2(NaCl)3Na33+ as an example. The precursor ion first loses all attached NaCl molecules, resulting in M2Na33+. The triply charged dimer then fragments via Coulomb explosion into MNa22+ and MNa+. There is no evidence for a Coulomb fission of the precursor ion itself, which would result in singly and doubly charged monomers containing neutral salt units (M(NaCl)0-3Na22+ and M(NaCl)0-3Na+). The ZnPcTetCr dimer is therefore comparatively stable, with the (NaCl)3 cluster only weakly bound to it. This result is somewhat unexpected; as the sodium ions are small enough to be completely encapsulated by the crown ether moieties,39, 49-51 they should not be able to form a sandwich complex with the crown ether unit of a second ZnPcTetCr molecule.52 Thus, we expected at least one Cl− ion to be in a bridging position between either the central zinc atoms or two Na+ containing crown ether units of the two ZnPcTetCr molecules. The ease in which all the chloride ions are split off as NaCl, however, leads us to conclude that the neutral salt molecules are attached on the outside of the ZnPcTetCr dimer, M2Na33+ (cf. Scheme 1).

Figure 4. a) CID mass spectrum of M2(NaCl)3Na33+ (m/z 1091).



Scheme 1. Possible structure of a triply charged dimer M2(NaCl)nNa33+ and its fragmentation (CID).

As mentioned before, in solution phthalocyanines and their derivatives are known to form aggregates due to π–π-interactions between the macrocyclic aromatic cores.1 We have recently shown that ZnPcTetCr is also able to form large stacks in the gas phase in the absence of metal cations.16 These clusters are held together by electrostatic interactions between neutral molecules and radical cations. In the current case, no radical ions are involved in forming the aggregates. The dimers and trimers are probably held together mainly by π–π-interactions between the phthalocyanines. And even though the sodium ions are small enough to be completely embedded in the [18]crown-6-moieties and therefore cannot attach a second crown ether, they may provide some electrostatic attraction, thus contributing to the stability of the aggregates. Judging from their CID mass spectra, all the doubly and triply charged dimers and trimers are relatively stable and dissociate only after all the attached NaCl molecules are split off. Only for the highest charged aggregates, M2(NaCl)nNa44+ and M3(NaCl)nNa5+, the charge repulsion between the sodium cations is large enough to separate the ZnPcTetCr oligomers in the first step upon activation. Figure 5 shows the CID mass spectrum of M3(NaCl)8Na55+ (m/z 1025) as an example. Enlargements of the relevant mass ranges can be found in the Supporting Information (Fig. S9). The precursor ion clearly does not undergo salt loss, but preferentially dissociates via Coulomb explosion into the doubly charged monomer and triply 12 ACS Paragon Plus Environment

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charged dimer. The number of attached NaCl molecules is divided among the product ions, resulting in a broad distribution of fragment ions, M(NaCl)0-7Na22+ and M2(NaCl)1-8Na33+. To a much lesser degree, the Coulomb fission into the triply charged monomers M(NaCl)0-3Na33+ and the doubly charged dimers M2(NaCl)1-7Na22+ is also observed. The reason for the low abundance of these product ions may be the less favorable charge distribution between fragments. As discussed above, the third sodium cation is less tightly bound than the first two; the triply charged monomer is therefore less stable than its doubly charged equivalent. Secondary fragmentation of these ions likely contributes to the high abundance of MNa22+. NaCl and/or (NaCl)2 losses from the first generation product ions also influence the ion distribution.

Figure 5. CID mass spectrum of M3(NaCl)8Na55+ (m/z 1025), acquired with the QTOF.

The preferred fragmentation pathways of the aggregates in the positive ion modes are summarized in Table 2. In short, we can conclude from the CID mass spectra that i) the charge carrying sodium ions are tightly bound inside the crown ether moieties, ii) the ZnPcTetCr dimers and trimers are held together by π–π-interactions between the aromatic cores and possibly electrostatic interactions with the embedded sodium cations, and iii) all the



neutral NaCl molecules are only weakly attached on the outside of the ZnPcTetCr aggregates in the form of small salt clusters.

Table 2. Preferred fragmentation pathways of the positive ions. monomers

dimers

trimers

ions MNa+ MNa22+ M(NaCl)nNa22+ MNa33+ M(NaCl)nNa33+ M2(NaCl)nNa22+ M2(NaCl)nNa33+ M2(NaCl)nNa44+ M3(NaCl)nNa33+ M3(NaCl)nNa44+

M3(NaCl)nNa55+

CID loss of Na+ sequential loss of NaCl and/or (NaCl)2 → MNa22+ loss of Na+ sequential loss of NaCl and/or (NaCl)2 → MNa33+ sequential loss of NaCl and/or (NaCl)2 → M2Na22+ Coul.a → MNa+ n = 1 Coul.a: n ≥ 2 loss of NaCl → M2Na33+ Coul.a n = 2–4 Coul.a; n = 4–5 sequential loss of NaCl sequential loss of NaCl → M3(NaCl)1–2Na33+ Coul.a Coul.a → predominately M2(NaCl)nNa33+ and MNa+, and M(NaCl)n1Na22+ and M2(NaCl)n2Na22+ b Coul.a → predominately M(NaCl)n1Na22+ and M2(NaCl)n2Na33+

a

Coul. = Coulomb explosion

b

see Supporting Information Fig. S10.

Negative-ion mode When the ZnPcTetCr solution with excess NaCl is sprayed in the negative ion mode, mainly singly charged monomers M(NaCl)0-9Cl− are observed (Figure 6a and Supporting Information, Figure S11). In less abundance, doubly charged dimers M2(NaCl)4-18Cl22− are also produced. Additionally, in the softer conditions and wider mass range of the QTOF, doubly charged trimers (M3(NaCl)9-20Cl22−) and triply charged tetramers and pentamers (M4(NaCl)14-27Cl33−, M5(NaCl)19-29Cl33−) are observed (cp. Figure 6b, Table 3 and Supporting Information, Figure S12).


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Figure 6. Negative ion mode ESI mass spectra of ZnPcTetCr in DCM/ACN with a tenfold excess of NaCl as observed on the QIT (a) and on the QTOF (b).

Table 3. Observed adducts in the negative ion mode (n.o. = not observed).

monomers dimers trimers tetramers pentamers

ions

m/z rangea

M(NaCl)nCl− M2(NaCl)nCl22− M3(NaCl)nCl22− M4(NaCl)nCl33− M5(NaCl)nCl33−

1049–2075 1667–2076 2570–2892 2328–2581 2930–3125

observed in observed in QIT (n = …) QTOF (n = …) 0–9 0–9 7–15 4–18 n.o. 9–20 n.o. 14–27 n.o. 19–29

a

Peak with the highest intensity of the smallest cluster to peak with highest intensity of largest observed cluster

Compared to the positive ion mode, the ZnPcTetCr aggregates are larger (up to five molecules) in the negative ion mode and attach a much larger number of neutral NaCl units (up to 29 instead of 11 in positive ion mode). However, the highest charge state observed in 15 ACS Paragon Plus Environment


the negative ion mode is smaller than in positive ion mode (3− vs. 5+). Note also, that the overall intensity of the ions was much lower than in the positive ion mode and long accumulation times were needed to obtain a spectrum with reasonably low signal-to-noiseratio. Again, CID mass spectra were obtained to gain insight into the structure of the aggregates. However, a majority of the ions were too small in intensity and could not be subjected to CID successfully. Representative CID mass spectra of the aggregates are shown in the following and in the Supporting Information (Figures S13–S15). The singly charged monomer MCl− dissociates via HCl loss, resulting in a deprotonated molecule [M – H]− (Figure 7a). HCl loss is only observed for this ion, all the aggregates containing neutral NaCl show a different fragmentation behavior: upon activation, the singly charged monomers lose all the attached neutral NaCl molecules in one step, leaving MCl− as the only fragment ion. Figure 7b and c show the CID mass spectra of M(NaCl)Cl− and M(NaCl)6Cl− as an example. The same behavior is observed for all the singly charged monomers. However, the aggregates with an odd number of attached NaCl molecules show a second, less abundant fragmentation pathway; they can lose all but one NaCl, yielding M(NaCl)Cl−. The predominant dissociation is nevertheless the loss of the complete neutral cluster (see Figure S13 of the Supporting Information).


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Figure 7. CID mass spectra of a) MCl−, b) M(NaCl)Cl− and c) M(NaCl)6Cl− (Only fragment ions of the single charged precursor are shown. For full spectrum see Figure S13d of the Supporting Information).

The doubly charged dimers M2(NaCl)nCl22− show a similar preference for one particular fragmentation pathway. Figure 8a shows the CID mass spectrum of M2(NaCl)13Cl22− as an example. The precursor ion dissociates via Coulomb explosion into the singly charged salt cluster (NaCl)13Cl− and the counter ion M2Cl−. The salt cluster can then fragment further, sequentially losing NaCl and/or (NaCl)2. Note that both clusters (NaCl)13Cl− and (NaCl)9Cl− are magic number clusters,21 i.e. they are more stable than other cluster sizes. These clusters are therefore preferentially formed in the fragmentation, while the intensities of the clusters with n = 10-12 barely exceed the noise level. The counter-ion of the initial Coulomb 17 ACS Paragon Plus Environment


explosion, M2Cl−, also dissociates further into MCl− via loss of a neutral molecule. This fragmentation indicates that the dimer is probably bridged by the chloride ion, which is bound to both central zinc atoms (cf. Scheme 2, top). 53 It is also possible that the Pcs are only held together by π–π-interactions and both the cluster and the charge carrying anions are weakly attached to the zinc atoms from the outside (cf. Scheme 2, bottom). The initial loss of the cluster (NaCl)nCl− would still generate the product ion M2Cl−, however, secondary fragmentation would result in a neutral Pc dimer and a single Cl− ion, which is too small to be detected by our instrument. Though there is no direct evidence for the occurrence of such ions, their facile secondary dissociation would explain the rather large intensity difference between the counter-ions of the initial Coulomb explosion. However, mass discrimination also accounts for the intensity difference to some extent, i.e. over such a large m/z range low and high mass ions cannot be detected with the same sensitivity. All the other doubly charged dimers we were able to isolate and subject to CID show the same fragmentation behavior (see Figures S13 and S14 of the Supporting Information).


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Figure 8. CID mass spectra of a) M2(NaCl)13Cl22− and b) M3(NaCl)13Cl22−, acquired with the QTOF. The inset in b) shows an enlargement overlaid with the simulated isotope pattern of M3Cl− in orange.

Scheme 2. Possible structures and fragmentation pathways (CID) of M2(NaCl)nCl22−. An example for the dissociation of the doubly charged trimers is shown in Figure 8b. The precursor M3(NaCl)13Cl22− fragments via the loss of the complete cluster (NaCl)13Cl−. The salt-cluster dissociates further, but only the magic-number cluster (NaCl)9Cl− is clearly discernible. The counter ion of the initial Coulomb explosion, M3Cl− (m/z 4579), is shown in the inset of Figure 8b, overlaid with its simulated isotope pattern. Note that M3Cl− can only be 19 ACS Paragon Plus Environment


observed if the instrument is tuned to detect high mass ions. This, however, compromises the measurement of the low mass fragment ions, causing a drop in the intensity of (NaCl)13Cl− and the disappearance of (NaCl)9Cl−. Due to this mass discrimination effect, Figure 8b is actually a combination of two different CID mass spectra of M3(NaCl)13Cl22−. To acquire the overview spectrum, the instrument was tuned to detect lower masses; for the inset it was tuned to detect the high mass region (see Supporting Information, Figures S15b, and c, for the complete spectrum with these settings). Even with these adjustments, however, the intensity of M3Cl− is very low and a long acquisition time was required to reduce the noise level sufficiently to detect it. This is probably due both to the mass discrimination effect and secondary fragmentation of the ion. MCl− as a possible second-generation product ion is observed in similarly low intensity (see Supporting Material, Figure S15c). In addition to M3Cl− and MCl−, several other singly charged monomers M(NaCl)nCl− (with n = 1, 2, 5, 6, 13) were also observed with these settings, though also with comparably low signal-to-noise ratios. These are the result of a second, much less favored fragmentation pathway, which probably proceeds via the loss of M2Cl− (formally; the M2Cl− ion itself is not observed) and the subsequent dissociation of the remaining M(NaCl)13Cl−. Only two other doubly charged trimers could be successfully subjected to CID (see Figure S15d–g of the Supporting Information). They all follow the same fragmentation pathway as M3(NaCl)13Cl22−, i.e. the loss of a singly charged salt cluster, preferentially a magic number cluster. Table 4. Preferred fragmentation pathways of the negative ions.

monomers dimers trimers a

ions MCl− M(NaCl)nCl− M2(NaCl)nCl22− M3(NaCl)nCl22−

CID loss of HCl loss of (NaCl)n or (NaCl)n−1 Coul.a → predominately (NaCl)nCl− and M2Cl− Coul.a → predominately (NaCl)nCl− and M3Cl−

Coul. = Coulomb explosion 20 ACS Paragon Plus Environment

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From the obtained CID mass spectra, which are summarized in Table 4, we can draw several conclusions concerning the structure of the negatively charged ions. All Na+ ions contained in these aggregates are part of the neutral NaCl cluster, none are embedded in the crown ether moieties. Only very few of the aggregates retain a single NaCl unit upon activation, of which the Na+ ion could be bound to a crown ether. In most of these cases, however, a magic number cluster is generated during the fragmentation. The NaCl therefore most likely remains with the Pc only to allow the formation of an exceptionally stable cluster fragment. If no sodium ion is embedded in the crown ethers, the only reasonable point of attachment for the charge carrying chloride ions is the central zinc atom of the phthalocyanine. The dimers M2(NaCl)nCl22− are either bridged by one chloride ion or held together only by π–π interactions. One or both anions are attached on the outside of the dimer and probably serve as an anchor for the neutral NaCl molecules. These are only weakly bound and easily lost as one cluster upon activation. The structure of the doubly charged trimers M3(NaCl)nCl22− is similarly ambiguous. The trimers are most likely the result of π–π stacking of the Pcs, with both charge carriers and the cluster attached to the outside. If the three ZnPcTetCr molecules were bridged by the two charge carrying chloride ions and the neutral salt units are attached to the outside of the trimer, we would not expect the loss of (NaCl)nCl− to occur so easily. Another possible structure would be (NaCl)nCl− attached to the outside, leaving only one Cl− to bridge two ZnPcTetCr molecules and the third to be bound by π–π-interactions only. A fourth possibility would be the singly charged cluster sandwiched between two ZnPcTetCr molecules. The third ZnPcTetCr could then be attached via the second charge-carrying Cl− ion. None of these structures can be excluded based on the available data. Neither can we rule out possible rearrangement of the aggregates during their flight time.



Conclusions The positively and negatively charged aggregates of ZnPcTetCr have surprisingly little in common. In the positive ions, the charge-carrying Na+ ions are embedded in the crown ether moieties and the oligomers are mainly held together by π–π-interactions, possibly aided by electrostatic attraction between occupied and empty crown ethers. In contrast, in the negatively charged ions the crown ether units contain no sodium ions and the dimers are at least partially connected by chloride ions bridging the central zinc atoms. Even the attached NaCl clusters behave differently. Upon activation, the positive ions fragment via NaCl/(NaCl)2 loss, while the negative ions release the entire cluster in one step. All these dissimilarities are a result of the different structures of the aggregates. However, the question remains how such diverse aggregates can be generated simply by reversing the polarity of the ESI source. Explaining the origin of the positively charged ions is rather straightforward. Due to the excess NaCl available and the high affinity of crown ethers for alkali metal ions, we assume that the majority of ZnPcTetCr molecules contain one or more sodium ions in the initial solution. These pre-charged molecules are stable and easily transferred into the gas phase. The aggregates, however, do not exist in the initial solution, as the concentrations of both the Pcs and NaCl are too low to cause their clustering. The aggregates are therefore formed during the electrospray process. As the solvent evaporates from the terminal nanodroplets, the concentrations of ZnPcTetCr and NaCl increase and the molecules eventually cluster together. Konermann et al. recently showed that pure NaCl clusters are formed via this charge-residue mechanism (CRM) from an aqueous solution. 28 According to their molecular dynamics (MD) simulations, excess charge is removed from the droplets via loss of single, solvated Na+ ions in the positive ion mode and Cl− ions in the negative ion mode. Small clusters are only ever released from highly charged droplets in the negative ion mode (NaCl2−). Thus the composition of the emerging ions is mainly determined 22 ACS Paragon Plus Environment

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by the content of the initial droplet. The same mechanism is probably responsible for the aggregate formation in our case in the positive ion mode. The sodium ions embedded in the crown ethers and the central zinc atom of the Pc attract the Cl− ions, while the remaining empty crown ethers provide a favorable interaction for the Na+ ions in the droplet. The precharged ZnPcTetCr molecules can therefore serve as a seed crystal for the NaCl clustering. With several points of attachment being available, the final aggregates probably consist of several smaller clusters bound to various points of the charge-carrying ZnPcTetCr. This would also explain the preferred loss of small NaCl/(NaCl)2 units upon activation. The generation of the negative ions is more difficult to explain. Despite the tenfold excess of NaCl, none of the crown ether moieties in these aggregates contains a Na+ ion. The bond between [18]crown-6 and Na+ is comparatively strong; the bond dissociation energy (BDE) was experimentally determined by Armentrout and co-workers to be 300 kJ mol−1. 40, 41 It is therefore highly unlikely that sodiated ZnPcTetCr molecules release all of their cations during the electrospray process. All the observed negative ions consequently originate from the small minority of remaining neutral ZnPcTetCr, which do not even capture a Na+ ion in the final stages of droplet evaporation. This would explain the overall low intensities of the negatively charged ions and the long accumulation time required to obtain a spectrum with reasonable signal-to-noise-ratio. With no sodium cations contained in the crown ether moieties, the only reasonable point of attachment for the NaCl clusters is the central zinc atom of the Pc. Thus, only one large cluster is formed, which is easily lost upon activation.

Acknowledgments The authors thank the Deutsche Forschungsgemeinschaft (DFG) – SFB 953 “Synthetic Carbon Allotropes” for financial support. We are also grateful for the financial support of the 23 ACS Paragon Plus Environment


MINECO, Spain (CTQ2014-52869-P) and Comunidad de Madrid, Spain (FOTOCARBON, S2013/MIT-2841). Supporting Information. Additional ESI mass and CID spectra.


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References

(1) Snow, A. W., Phthalocyanine Aggregation, in The Porphyrin Handbook, Kadish, K.M.; Smith, K. M.; Guilard, R. editors, volume 17 / Phthalocyanines: Properties and Materials, chapter 109, Academic Press 2006, 1st edition, 129–176. (2) Hendriks, R.; Sielcken, O. E.; Drenth, W.; Nolte, R. J. M., Polytopic Ligand Systems: Synthesis and Complexation Properties of a ’Crowned’ Phthalocyanine, J. Chem. Soc., Chem. Commun. 1986, 1464–1465. (3) Kobayashi, N.; Nishiyama, Y., A Copper Phthalocyanine with Four Crown Ether Voids, J. Chem. Soc., Chem. Commun. 1986, 1462–1463. (4) Koray, A. R.; Ahsen, V.; Bekâroğlu, Ö., Preparation of a Novel, Soluble Copper Phthalocyanine with Crown Ether Moieties, J. Chem. Soc., Chem. Commun. 1986, 932–933. (5) Kobayashi, N.; Lever, A. B. P., Cation or Solvent-Induced Supermolecular Phthalocyanine Formation: Crown Ether Substituted Phthalocyanines, J. Am. Chem. Soc. 1987, 109, 7433–7441. (6) Sielcken, O. E.; Van Tilborg, M. M.; Roks, M. F. M.; Hendriks, R.; Drenth, W.; Nolte, R. J. M., Synthesis and Aggregation Behavior of Hosts Containing Phthalocyanine and Crown Ether Subunits, J. Am. Chem. Soc. 1987, 109, 4261–4265. (7) Reddy, D.; Chandrashekar, T., Optical and ESR Studies on Dimerization of Metallotetra-Crowned Phthalocyanines, Polyhedron 1993, 12, 627–633. (8) Kobayashi, N.; Togashi, M.; Osa, T.; Ishii, K.; Yamauchi, S.; Hino, H., Low Symmetrical Phthalocyanine Analogues Substituted with Three Crown Ether Voids and Their Cation-Induced Supermolecules, J. Am. Chem. Soc. 1996, 118, 1073–1085. (9) Nikolaitchik, A. V.; Korth, O.; Rodgers, M. A. J., Crown Ether Substituted Monomeric and Cofacial Dimeric Metallophthalocyanines. 1. Photophysical Studies of the Free Base, Zinc(II), and Copper(II) Variants, J. Phys. Chem. A 1999, 103, 7587–7596. (10) Engelkamp, H.; Middelbeek, S.; Nolte, R. J. M., Self-Assembly of Disk-Shaped Molecules to Coiled-Coil Aggregates with Tunable Helicity, Science 1999, 284, 785–788. (11) D’Souza, F.; Maligaspe, E.; Ohkubo, K.; Zandler, M. E.; Subbaiyan, N. K.; Fukuzumi, S., Photosynthetic Reaction Center Mimicry: Low Reorganization Energy Driven Charge Stabilization in Self-Assembled Cofacial Zinc Phthalocyanine Dimer–Fullerene Conjugate, J. Am. Chem. Soc. 2009, 131, 8787–8797. (12) Lederer, M.; Hahn, U.; Fernández-Ariza, J.; Trukhina, O.; Rodríguez-Morgade, M. S.; Dammann, C.; Drewello, T.; Torres, T.; Guldi, D. M., Tuning Electron Donor–Acceptor Hybrids by Alkali Metal Complexation, Chem. – Eur. J. 2015, 21, 5916–5925. 25 ACS Paragon Plus Environment


(13) Lederer, M.; Hahn, U.; Strub, J.-M.; Cianférani, S.; Van Dorsselaer, A.; Nierengarten, J.-F.; Torres, T.; Guldi, D. M., Probing Supramolecular Interactions between a Crown Ether Appended Zinc Phthalocyanine and an Ammonium Group Appended to a C60 Derivative, Chem. – Eur. J. 2016, 22, 2051–2059. (14) Gantchev, T. G.; Beaudry, F.; Van Lier, J. E.; Michel, A. G., Semi-Empirical Molecular Orbital Studies of Porphine and Phthalocyanine Derivatives, to Simulate their Intermolecular Interactions, Int. J. Quantum Chem. 1993, 46, 191–210. (15) Thordarson, P.; Nolte, R. J. M.; Rowan, A. E., Self-Assembly of Chiral Phthalocyanines and Chiral Crown Ether Phthalocyanines, in The Porphyrin Handbook, Kadish, K.M.; Smith, K. M.; Guilard, R. editors, volume 18 / Multiporphyrins, Multiphthalocyanines, and Arrays, chapter 115, Academic Press 2006, 281–301. (16) Kellner, I. D.; Hahn, U.; Dürr, M.; Torres, T.; Ivanović-Burmazović, I.; Drewello, T., Aggregation of a Crown Ether Decorated Zinc-Phthalocyanine by Collision-Induced Desolvation of Electrospray Droplets, J. Phys. Chem. A 2015, 119, 11454–11460. (17) Hwang, H. J.; Sensharma, D. K.; El-Sayed, M. A., Kinetic Energy Release Distribution and the Mechanism for Evaporation of One and Two CsI Molecules from Sputtered Cs(CsI)n+ Clusters, Chem. Phys. Lett. 1989, 160, 243–249. (18) Drewello, T.; Herzschuh, R.; Stach, J., Direct Fission Versus Sequential Evaporation Mechanism of Sputtered Caesium Iodide Cluster Ions, Z. Phys. D Atom Mol. Cl. 1993, 28, 339–343. (19) Wang, G.; Cole, R. B., Solvation Energy and Gas-Phase Stability Influences on Alkali Metal Cluster Ion Formation in Electrospray Ionization Mass Spectrometry, Anal. Chem. 1998, 70, 873–881. (20) Zhang, D.; Cooks, R., Doubly Charged Cluster Ions [(NaCl)m(Na)2]2+: Magic Numbers, Dissociation, and Structure, Int. J. Mass Spectrom. 2000, 195/196, 667–684. (21) Hao, C.; March, R. E.; Croley, T. R.; Smith, J. C.; Rafferty, S. P., Electrospray Ionization Tandem Mass Spectrometric Study of Salt Cluster Ions. Part 1 – Investigations of Alkali Metal Chloride and Sodium Salt Cluster Ions, J. Mass Spectrom. 2001, 36, 79–96. (22) Aguado, A., An ab Initio Study of the Structures and Relative Stabilities of Doubly Charged [(NaCl)m(Na)2]2+ Cluster Ions, J. Phys. Chem. B 2001, 105, 2761–2765. (23) Ince, M.; Perera, B.; Stipdonk, M. V., Production, Dissociation, and Gas Phase Stability of Sodium Fluoride Cluster Ions Studied Using Electrospray Ionization Ion Trap Mass Spectrometry, Int. J. Mass Spectrom. 2001, 207, 41–55. (24) Herzschuh, R.; Drewello, T., The Fragmentation Dynamics of Small Cs(CsI)n+ Cluster Ions Under Low-Energy Multiple Collision Conditions, Int. J. Mass Spectrom. 2004, 233, 355–359, special Issue: In honour of Tilmann Mark.


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(25) Bai, J.; Liu, Z.; Shi, L.; Liu, S., Studies on the Doubly Charged Cluster Ions of Sodium and Potassium Nitrates by Electrospray Ionization Tandem Mass Spectrometry, Int. J. Mass Spectrom. 2007, 260, 75–81. (26) Feketeová, L.; O’Hair, R. A. J., Comparison of Collision- Versus Electron-Induced Dissociation of Sodium Chloride Cluster Cations, Rapid Commun. Mass Spectrom. 2009, 23, 60–64. (27) Bradshaw, J. A.; Gordon, S. L.; Leavitt, A. J.; Whetten, R. L., Adsorption of Water Molecules on Selected Charged Sodium–Chloride Clusters, J. Phys. Chem. A 2012, 116, 27– 36. (28) Konermann, L.; McAllister, R. G.; Metwally, H., Molecular Dynamics Simulations of the Electrospray Process: Formation of NaCl Clusters via the Charged Residue Mechanism, J. Phys. Chem. B 2014, 118, 12025–12033. (29) Schachel, T. D.; Metwally, H.; Popa, V.; Konermann, L., Collision-Induced Dissociation of Electrosprayed NaCl Clusters: Using Molecular Dynamics Simulations to Visualize Reaction Cascades in the Gas Phase, J. Am. Soc. Mass Spectrom. 2016, 27, 1846– 1854. (30) Striegel, A. M.; Timpa, J. D.; Piotrowiak, P.; Cole, R. B., Multiple neutral alkali halide attachments onto oligosaccharides in electrospray ionization mass spectrometry, Int. J. Mass Spectrom. Ion Processes 1997, 162, 45 – 53. (31) Kellner, I. D.; Drewello, T., Influence of Single Skimmer Versus Dual Funnel Transfer on the Appearance of ESI-Generated LiCl Cluster/β-Cyclodextrin Inclusion Complexes, J. Am. Soc. Mass Spectrom. 2015, 26, 1328–1337. (32) D’Souza, F.; Maligaspe, E.; Sandanayaka, A. S. D.; Subbaiyan, N. K.; Karr, P. A.; Hasobe, T.; Ito, O., Photochemical Charge Separation in Supramolecular Phthalocyanine – Multifullerene Conjugates Assembled by Crown Ether-Alkyl Ammonium Cation Interactions, J. Phys. Chem. A 2010, 114, 10951–10959. (33) Danell, R. M.; Danell, A. S.; Glish, G. L.; Vachet, R. W., The Use of Static Pressures of Heavy Gases Within a Quadrupole Ion Trap, J. Am. Soc. Mass Spectrom. 2003, 14, 1099– 1109. (34) Shaffer, S. A.; Tang, K.; Anderson, G. A.; Prior, D. C.; Udseth, H. R.; Smith, R. D., A Novel Ion Funnel for Focusing Ions at Elevated Pressure Using Electrospray Ionization Mass Spectrometry, Rapid Commun. Mass Spectrom. 1997, 11, 1813–1817. (35) Julian, R. R.; Mabbett, S. R.; Jarrold, M. F., Ion Funnels for the Masses: Experiments and Simulations with a Simplified Ion Funnel, J. Am. Soc. Mass Spectrom. 2005, 16, 1708– 1712. (36) Kelly, R. T.; Tolmachev, A. V.; Page, J. S.; Tang, K.; Smith, R. D., The Ion Funnel: Theory, Implementations, and Applications, Mass Spectrom. Rev. 2010, 29, 294–312. 27 ACS Paragon Plus Environment


(37) Pedersen, C. J., Cyclic Polyethers and Their Complexes with Metal Salts, J. Am. Chem. Soc. 1967, 89, 2495–2496. (38) Pedersen, C. J., Cyclic Polyethers and Their Complexes with Metal Salts, J. Am. Chem. Soc. 1967, 89, 7017–7036. (39) Pedersen, C. J., The Discovery of Crown Ethers (Noble Lecture), Angew. Chem., Int. Ed. Engl. 1988, 27, 1021–1027. (40) Armentrout, P. B., Cation–Ether Complexes in the Gas Phase: Thermodynamic Insight Into Molecular Recognition, Int. J. Mass Spectrom. 1999, 193, 227–240. (41) More, M. B.; Ray, D.; Armentrout, P. B., Intrinsic Affinities of Alkali Cations for 15Crown-5 and 18-Crown-6: Bond Dissociation Energies of Gas-Phase M+-Crown Ether Complexes, J. Am. Chem. Soc. 1999, 121, 417–423. (42) L’Her, M.; Pondaven, A., Electrochemistry of Phthalocyanines, in The Porphyrin Handbook, Kadish, K.M.; Smith, K. M.; Guilard, R. editors, volume 16 / Phthalocyanines: Spectroscopic and Electrochemical Characterization, chapter 104, Academic Press 2006, 1st edition, 117–170. (43) Van Berkel, G. J.; Vilmos, K., Using the Electrochemistry of the Electrospray Ion Source, Anal. Chem. 2007, 79, 5510–5520. (44) Schäfer, M.; Drayß, M.; Springer, A.; Zacharias, P.; Meerholz, K., Radical Cations in Electrospray Mass Spectrometry: Formation of Open-Shell Species, Examination of the Fragmentation Behaviour in ESI-MSn and Reaction Mechanism Studies by Detection of Transient Radical Cations, Eur. J. Org. Chem. 2007, 2007, 5162–5174. (45) Hudgins, R. R.; Dugourd, P.; Tenenbaum, J. M.; Jarrold, M. F., Structural Transitions in Sodium Chloride Nanocrystals, Phys. Rev. Lett. 1997, 78, 4213–4216. (46) March, R. E., An Introduction to Quadrupole Ion Trap Mass Spectrometry, J. Mass Spectrom. 1997, 32, 351–369. (47) March, R. E., Quadrupole Ion Trap Mass Spectrometry: A View at the Turn of the Century, Int. J. Mass Spectrom. 2000, 200, 285–312. (48) Polce, M. J.; Beranová, v.; Nold, M. J.; Wesdemiotis, C., Characterization of Neutral Fragments in Tandem Mass Spectrometry: A Unique Route to Mechanistic and Structural Information, J. Mass Spectrom. 1996, 31, 1073–1085. (49) Hancock, R. D., A Molecular Mechanics Study of the Selectivity of Crown Ethers for Metal Ions on the Basis of Their Size, J. Inclusion Phenom. Mol. Recognit. Chem. 1994, 17, 63–80. (50) Maleknia, S.; Brodbelt, J., Gas-Phase Selectivities of Crown Ethers for Alkali Metal Ion Complexation, J. Am. Chem. Soc. 1992, 114, 4295–4298. 28 ACS Paragon Plus Environment

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(51) Glendening, E. D.; Feller, D.; Thompson, M. A., An Ab Initio Investigation of the Structure and Alkali Metal Cation Selectivity of 18-Crown-6, J. Am. Chem. Soc. 1994, 116, 10657–10669. (52) Nicoll, J. B.; Dearden, D. V., Reactions of Multidentate Ligands with Ligated Alkali Cation Complexes: Self-Exchange and "Sandwich" Complex Formation Kinetics of Gas Phase Crown Ether–Alkali Cation Complexes, Int. J. Mass Spectrom. 2001, 204, 171–183. (53) Hitzenberger, J. F.; Dammann, C.; Lang, N.; Lungerich, D.; Garcia-Iglesias, M.; Bottari, G.; Torres, T.; Jux, N.; Drewello, T., Making the Invisible Visible: Improved Electrospray Ion Formation of Metalloporphyrins/-phthalocyanines by Attachment of the Formate Anion (HCOO−), Analyst 2016, 141, 1347–1355.



Table of Contents Image


Page 30 of 42

O

O

O ofof O The Page Journal 31 42Physical Chemistry O O O

O

O

O

O

O

N 1 N N 2 Zn N N 3 N N 4 N 5 O O O O 6 O O O O 7 O O O 8 O ACS 9 Paragon Plus Environment ZnPcTetCr 10 C72H88N8O24Zn 11 Exact mass: 1512.520

The Journal of Physical Chemistry Page 32 of 42 1 2 3

ACS Paragon Plus Environment a)

b)

c)

Intens. [P]

M•=•ZnPcTetCr Pagea) 33 of 42

M2rNaCl)0-2Na22+


100

1537.4

MNa+

80

1 260 3 440 5 620 7 80 Intens. 9[P] 10 100 11 12 80 13 14 60 15 16 40 17 18 20 19 200

MrNaCl)0-1Na22+ 779.3

404.2

768.3

1032.6

MNaK2+

MNar2+)•

M2NaK2+

M2rNaCl)0-2Na33+ M2Na2K3+

1566.8

1051.9

809.2

MrNaCl)0-7Na22+

b)

779.3

M2rNaCl)2-5Na44+

MrNaCl)0-2Na33+

809.2 838.2

M2rNaCl)1-9Na33+

527.8

1110.5

M3rNaCl)6-8Na5

5+

M3rNaCl)4-11Na44+ ACS Paragon Plus Environment 867.2 897.1

547.8 400

600

800

1261.6

1013.1 1000

1200

1400

MNa+ M2rNaCl)1-4Na22+ M3rNaCl)3-6Na33+ 1537.4 1600

m/z

Intens. [%] 100

MNa+ a) 1535.434 of 42 Page


80

160 2 340 420 5 60 7 Intens. 8[%] 100 9 80 10 11 60 12 13 40 14 20 15 160

− CH2O 765.2

MNa22+

− Na+

677.7

600

1359.3 800

MNa2

1000

1200

1507.4

1400

1600

2+

b)

779.5

MNa33+ 527.2 600

ACS Paragon Plus Environment − Na+

− Na+ 800

m/z

1000

1200

MNa+

1535.4 1400

1600

m/z

Page 35 of 42 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Intens. [%] 100

MNa22+

a)

779.5

80 60 40

M(NaCl)Na2 20

NaCl

809.2

M(NaCl)2Na22+

2+

838.2

NaCl

M(NaCl)3Na22+ NaCl

0 760 Intens. [%] 100

780

MNa2

800

820

840

860

880

900

2+

m/z

b)

779.5

80 60

M(NaCl)2Na22+

40

838.2 20

M(NaCl)4Na22+

(NaCl)2

(NaCl)2

0 760

780

800

820

840

ACS Paragon Plus Environment

860

880

900

m/z

Intens. [p] 100

M2(NaCl)Na33+ 1052.2 The Journal of Physical Chemistry 3+ M2(NaCl) 2Na3 1071.5

80

160 2 340 420 5 60

Page 36 of 42

CoulombuExplosion

MNa22+ 779.2

3+ M2Na33+ ACS Paragon M2(NaCl) Plus3Na Environment 3

MNa+

1537.4

1032.6 800

900

1000

1100

1200

1300

1400

1500

1600 m/z

Intens. [%]

Page 37 of 42 100

80

160 2 340 420 M(NaCl)0-3Na33+ 5 547.204 60 600

M(NaCl)0-7Na22+ The Journal of Physical Chemistry 779.325 M2(NaCl)1-8Na33+ 0 3 1091.399 M3(NaCl)8Na55+ 4 5

2 838.286

1

800

3

4

MNa+

5 ACS Paragon 2 Plus 6 Environment 8 7 6 7 1 1000

1200

M2(NaCl)1-7Na22+ 1400

1600

1800m/z

Intens. [%] 100

a) Page 38 of 42

− The Journal of Physical Chemistry M(NaCl) 0-8Cl

1549.5

80

1 260 3 440 5 620 7 80 9 Intens. 10 [%] 11 100 12 13 80 14 15 60 16 17 40 18 20 19 20 210

M2(NaCl)7-15Cl22− 1607.4

1841.2 1665.4

1550

1600

1650

1700

1899.1

1783.2

1725.3 1750

1800

1850

1959.0

1900

1950

2000

M(NaCl)0-9Cl−

m/z

b)

1549.478

M2(NaCl)4-18Cl22− 1841.268 1607.435

1901.225

1959.183

1667.392 1600

M3(NaCl)9-20Cl22−

1800

2000

3− MEnvironment 4(NaCl)14-27Cl3 ACS Paragon Plus

2425.379

2200

2400

M5(NaCl)19-29Cl33− 3008.154

2687.455 2600

2800

3000

m/z

Intens. [%] 1511.5 [M Page of 42 100 39

− H]−

a)


80

160 2 340 420 5 60 Intens. 7[%] 100 8 980 10 60 11 12 40 13 20 14 150 16 Intens. 17 [%] 100 18 19 80 20 60 21 22 40 23 20 24 25 0 26

MCl−

b)

1549.4

M(NaCl)Cl− 1520

MCl

1540

1560

1580

1600

1620

1640

1660

1680 m/z

−

c)

1549.5

ACS Paragon Plus Environment 1550

1600

1650

1700

1750

M(NaCl)6Cl− 1800

1850

1900

m/z

Intens. [p] 100 80

no=o13 (NaCl)nCl−

160 2 no=o9 340 no=o8 420 no=o7 no=o11 5 60 500 7 Intens. no=o13 [p] 8100 794.423 9 80 10 11 (NaCl)nCl− 60 12 40 13 14 20 no=o9 15 560.583 160 500

1000

a) Page 40 of 42


794.415

CoulomboExplosion M2(NaCl)13Cl22− M2Cl−

MCl−

3064.985

1549.468 1000

1500

2000

2500 4579.477

4570.0

4575.0

4580.0

3000 m/z

b)

M3Cl−o

4585.0

4590.0

m/z

ACS Paragon Plus Environment M3(NaCl)13Cl22− 1500

2000

2500

3000

3500

4000

4500m/z

Page 41 of 42 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


2+ 3+ 3+

n +

n = Na+

= Cl


+

−

2−


Page 42 of 42

−

−

− 1 2 3 4 5 6 7 8 9 10

+

2− −

−

−


−

+

Salt Cluster Attachment to Crown Ether Decorated Phthalocyanines in

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