Soft crystals, which are defined as flexible response systems with high structural order, respond to gentle stimuli such as vapor exposure and rubbing but maintain their ordered structures and exhibit remarkable visual changes in their shape, color, and luminescence. This article focuses on the soft crystals composed of platinum（Ⅱ） complexes bearing aromatic ligands that exhibit characteristic luminescence by assembly. When the complex units are stacked with short Pt…Pt contacts, a new emission state called ³MMLCT （i.e. metal-metal-to-ligand charge transfer） are generated on the basis of the Pt…Pt electronic interaction, and the ³MMLCT energy can change by the slight deformation of the stacking structure in response to gentle stimuli. These properties make platinum（Ⅱ） complexes soft crystals, and the precise control of the Pt…Pt interaction and other intermolecular interactions enables the precise control of photofunctions beyond the existing limitation.

Porous materials with high surface areas are widely applied in industry from the viewpoint of separation, purification, and storage. Most reported porous materials are Metal-Organic Frameworks（MOFs）, Porous Organic Polymers（POPs）, and zeolites, which are macromolecular porous materials. On the other hand, we have been developing porous organic crystals based on pillar［n］arenes that we have developed originary. Since pillar［n］arenes have pores at the molecular level, it is clear which molecule is taken up. In addition to the selective uptake, functional groups can be easily introduced into pillar［n］arenes. With these characteristics, we have developed soft crystals that selectively take up vapors and show color or assembly state changes.

Crystalline-state polymerization often produce polymers with different structures compared to those produced by conventional polymerization. Crystalline-state polymerization can be classified into two types, topochemical polymerization and inclusion polymerization. In this context, we developed a new methodology to produce a polymer, in which a copolymerization of a host monomer and a guest monomer takes place, thus it can be regarded as a fusion of topochemical polymerization and inclusion polymerization. By using this new polymerization, the control of polymerization degree in step-growth polymerization, as well as the control of shape and network structure of a network polymer, have been achieved, which is reviewed in this chapter.

‘Softcrystals’ is the name of a group of new functional materials that can cause changes in luminescence properties and crystal phase-transitions by applying relatively weak external fields such as light irradiation, vapor exposure, and mechanical stimuli. The time-scale of these structural transitions are very widely. In this paper, we will introduce various time-resolved measurement systems using synchrotron radiation as structure-tracking methods for external field-responsive softcrystals.

Molecular crystals seem rigid, fragile, and lack flexibility. However, in spite of such an appearance, this decade has witnessed flexible responses of molecular crystals, induced by external stimuli such as light, heat, humidity, mechanical force, and so on. Such molecular crystals belong to the family of soft crystals due to the flexible features and the response to gentle stimulus. This article reviews the history and recent advances of photo- and thermo-mechanical soft crystals.

Photochromic compounds have attracted the attention of chemists not only for the scientific point of view but also for their potential application in light control material and optical switching devices and so on. So far, we have studied the relationship between the photochromic characteristic behavior and the crystal structures of organic photochromic compounds. As the next step, we designed a new type of cobalt complex soft crystals which have two kinds of photoreactive moieties in the crystalline-state; these are called dual photoreactive complexes. In situ control of crystalline-state photochromism of salicylideneaniline derivatives and spiropyran derivatives and solid-state photoreaction of azobenzene derivatives were achieved using this new type of the cobalt complex soft crystals.

Since 1999, SER-CAT has been working towards the concept of providing its members with a “Virtual Beamline”, which could be integrated into their daily workflow much like your X-ray lab down the hall.

We began investigating robotic crystal mounting automation in 2000 with Oceaneering Space Systems. In 2003, a highly modified Berkeley ALS Automounter was installed on 22BM. Using 22BM as a user-based testbed, the beamline and experiment control interface SERGUI was continually modified until a reliable, robust and user-friendly system was achieved. In 2006, the SER-CAT Virtual Beamline came online providing remote crystal screening and data collection capability on both 22ID（capacity 450 crystals）and 22BM（capacity 96 crystals）.

The SERGUI beam line control interface allows the direct remote access of SER-CAT beamline from their home labs including：1）beamline/goniometer optimization, 2）wavelength selection, 3）fluorescence scans, 4）automatic crystal centering and rastering, 5）automated crystal screening, 6）MAD/SAD/Helical data collection and others. Today over 95% of SER-CAT members routinely collect data remotely. SER-CAT has also implemented 12-hour shifts with 16-hours/day and 7-days/week of on-site user support to assist users for their remote accesses from home labs. Multiple Access Time（MAT）shifts have also been made available to SER-CAT members for fast turn-around and flexible data collection capabilities.

SER-CAT also provides its members the on-the-fly automated data processing using XDS, KYLIN and DIALS. HKL2000, XDS, MOSFLM, and DIALS for manual data processing. All user data can be remotely, quickly, reliably and securely downloaded from SER-CAT's Globus/GridFTP archive server to the users' home systems anywhere and anytime.

During the annual SER-CAT Symposium, awards are given out to recognize senior investigator's “Outstanding Science” and young investigator's “Outstanding Research Achievement” carried out at SER-CAT.