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Crystal chemistry and photomechanical behavior of 3,4-dimethoxycinnamic acid: correlation between maximum yield in the solid-state topochemical reaction and cooperative molecular motion.

Mishra MK, Mukherjee A, Ramamurty U, Desiraju GR - IUCrJ (2015)

Bottom Line: Form I exhibits photosalient behavior but this effect is absent in form II.It is suggested that both Schmidt-type and Kaupp-type topochemistry are applicable for the solid-state trans-cinnamic acid photodimerization reaction.Form II is more brittle, and its interlocked structure seems to favor Schmidt-type topochemistry with minimum molecular movement.

View Article: PubMed Central - HTML - PubMed

Affiliation: Solid State and Structural Chemistry Unit, Indian Institute of Science , Bangalore 560 012, India.

ABSTRACT
A new monoclinic polymorph, form II (P21/c, Z = 4), has been isolated for 3,4-dimethoxycinnamic acid (DMCA). Its solid-state 2 + 2 photoreaction to the corresponding α-truxillic acid is different from that of the first polymorph, the triclinic form I ([Formula: see text], Z = 4) that was reported in 1984. The crystal structures of the two forms are rather different. The two polymorphs also exhibit different photomechanical properties. Form I exhibits photosalient behavior but this effect is absent in form II. These properties can be explained on the basis of the crystal packing in the two forms. The nanoindentation technique is used to shed further insights into these structure-property relationships. A faster photoreaction in form I and a higher yield in form II are rationalized on the basis of the mechanical properties of the individual crystal forms. It is suggested that both Schmidt-type and Kaupp-type topochemistry are applicable for the solid-state trans-cinnamic acid photodimerization reaction. Form I of DMCA is more plastic and seems to react under Kaupp-type conditions with maximum molecular movements. Form II is more brittle, and its interlocked structure seems to favor Schmidt-type topochemistry with minimum molecular movement.

No MeSH data available.


Related in: MedlinePlus

Packing diagram of truxillic acid dimer. Note the O—H⋯O hydrogen-bonded carboxylic acid dimer synthons are shaded in light gray and C—H⋯O interactions are shaded in dark gray.
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fig3: Packing diagram of truxillic acid dimer. Note the O—H⋯O hydrogen-bonded carboxylic acid dimer synthons are shaded in light gray and C—H⋯O interactions are shaded in dark gray.

Mentions: The crystal structure of truxillic acid photodimer was also obtained (Table 1 ▸, Fig. 3 ▸) and it is constituted with O—H⋯O hydrogen-bonded carboxylic acid dimer synthons. This leads to the formation of one-dimensional chains which form a close-packed structure. C—H⋯O interactions also play a role in the packing, and are mainly between methoxy groups.


Crystal chemistry and photomechanical behavior of 3,4-dimethoxycinnamic acid: correlation between maximum yield in the solid-state topochemical reaction and cooperative molecular motion.

Mishra MK, Mukherjee A, Ramamurty U, Desiraju GR - IUCrJ (2015)

Packing diagram of truxillic acid dimer. Note the O—H⋯O hydrogen-bonded carboxylic acid dimer synthons are shaded in light gray and C—H⋯O interactions are shaded in dark gray.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4645110&req=5

fig3: Packing diagram of truxillic acid dimer. Note the O—H⋯O hydrogen-bonded carboxylic acid dimer synthons are shaded in light gray and C—H⋯O interactions are shaded in dark gray.
Mentions: The crystal structure of truxillic acid photodimer was also obtained (Table 1 ▸, Fig. 3 ▸) and it is constituted with O—H⋯O hydrogen-bonded carboxylic acid dimer synthons. This leads to the formation of one-dimensional chains which form a close-packed structure. C—H⋯O interactions also play a role in the packing, and are mainly between methoxy groups.

Bottom Line: Form I exhibits photosalient behavior but this effect is absent in form II.It is suggested that both Schmidt-type and Kaupp-type topochemistry are applicable for the solid-state trans-cinnamic acid photodimerization reaction.Form II is more brittle, and its interlocked structure seems to favor Schmidt-type topochemistry with minimum molecular movement.

View Article: PubMed Central - HTML - PubMed

Affiliation: Solid State and Structural Chemistry Unit, Indian Institute of Science , Bangalore 560 012, India.

ABSTRACT
A new monoclinic polymorph, form II (P21/c, Z = 4), has been isolated for 3,4-dimethoxycinnamic acid (DMCA). Its solid-state 2 + 2 photoreaction to the corresponding α-truxillic acid is different from that of the first polymorph, the triclinic form I ([Formula: see text], Z = 4) that was reported in 1984. The crystal structures of the two forms are rather different. The two polymorphs also exhibit different photomechanical properties. Form I exhibits photosalient behavior but this effect is absent in form II. These properties can be explained on the basis of the crystal packing in the two forms. The nanoindentation technique is used to shed further insights into these structure-property relationships. A faster photoreaction in form I and a higher yield in form II are rationalized on the basis of the mechanical properties of the individual crystal forms. It is suggested that both Schmidt-type and Kaupp-type topochemistry are applicable for the solid-state trans-cinnamic acid photodimerization reaction. Form I of DMCA is more plastic and seems to react under Kaupp-type conditions with maximum molecular movements. Form II is more brittle, and its interlocked structure seems to favor Schmidt-type topochemistry with minimum molecular movement.

No MeSH data available.


Related in: MedlinePlus